Caterpillar GC25 Lift Truck Service Manual - PDF DOWNLOAD

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Lift Trucks

Service Manual Liquefied Petroleum Gas Supplement 4G63 4G64 6G72

AA0001-ZZ9999 AA0001-ZZ9999 0A0001-0Z9999

For use with 4G63, 4G64 & 6G72 Engine Service Manuals.

99729-85100

INTRODUCTION LP-gas (Liquefied Petroleum gas) lift trucks are superior to gasoline lift trucks in many ways including cleaner emissions and higher fuel efficiency.

LP-gas is, however, more dangerous than gasoline when handled improperly.

This Service Manual contains operating instructions and maintenance procedures for the LP-gas device of Caterpillar LP-gas fuel lift trucks. To ensure safety and maximize the superb features of your lift truck, read this manual thoroughly.

The following mark and designation are used in this manual to call your attention to important instructions and cautions.

< Warning indication > CAUTION

Note

Indicates items that users must always observe in order to prevent injuries and damage to the vehicle and surrounding area.

Supplementary explanation

99729-85100

TABLE OF CONTENTS Types of LP-gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Guideline for selecting LP-gas for lift-truck engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 LP-gas knock rating and octane number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Adverse effects of olefins on LP-gas fuel system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Vapor pressure vs. temperature for mixture of propane and normal butane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Structure and Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 1. Outline of LP-gas device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2. LP-gas device layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 3. Main component structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 3.1. LP-gas tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 3.1.1. Pressure relief valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 3.1.2. Fixed liquid level gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 3.1.3. Service valve (LP-gas outlet valve) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 3.1.4. Fuel level indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 3.2. Filter (Vacuum fuel lock filter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 3.3. Hydrostatic relief valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 3.4. Converter (vaporizer) and LP-gas carburetor . . . . . . . . . . . . . . . . . . . . . . . . . .11 3.4.1. Converter (vaporizer) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 3.4..2. LP-gas carburetor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Actions to be taken in the event of a failure

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Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Disassembly and reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 1. Main components of LP-gas device (4G63, 4G64) . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 2. Main components of LP-gas device (6G72) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 3. Disassembly and reassembly of LP-gas carburetor /mixer . . . . . . . . . . . . . . . . . . . . . . .19 4. Disassembly and reassembly of converter/regulator (vaporizer) . . . . . . . . . . . . . . . . . .21 5. Disassembly and reassembly of LP-gas filter, Fuel lock . . . . . . . . . . . . . . . . . . . . . . . .27 Inspection and adjustment . . . . . . . . . .

1. LP-gas tank inspection . . . . . . . . . .

2. Filter inspection . . . . . . . . . . . . . . .

3. Converter (vaporizer) inspection and 4. Idle speed adjustment . . . . . . . . . .

5. Output power adjustment . . . . . . . .

6. Gas leak check procedure . . . . . . .

......... ......... ......... adjustment ......... ......... ......... i

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.33 .33 .33 .34 .35 .36 .36

CARB Tier 1 Emissions Control System (S-15G, 2001-2002 Model Year) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Outline of CARB Tier 1 LP-gas system . . . . . . . . . . . . .

2. CARB Tier 1 LP-gas layout . . . . . . . . . . . . . . . . . . . . . .

3. Main Component Illustrations . . . . . . . . . . . . . . . . . . . .

3.1. Electronic Control Units (ECU) (Version 1 & 2) . . .

3.2. Electronic Control Unit Illustration . . . . . . . . . . . . .

3.3. Oxygen Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4. Pedal Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.5. Engine Block Temperature Sensor . . . . . . . . . . . .

3.6. Mixer and Throttle Body Illustration . . . . . . . . . . . .

3.7. Three Way Catalytic Convertor . . . . . . . . . . . . . . .

3.8. Dash Light Illustration . . . . . . . . . . . . . . . . . . . . . .

3.9. Exploded view for use with Pneumatic type models 3.10. Exploded view for use with cushion type models . .

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Systems Operations 1. Explanation of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 Sub-system Operating Principles 1. Fuel Control . . . . . . . . . . . . . . .

2. Fuel Control Operation . . . . . . .

3. Throttle and Governor . . . . . . . .

4. Throttle and Governor Operation 5. Operating Specifications . . . . . .

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.46 .48 .49 .50 .50

System Adjustments 1. Diagnostic Kit Installation . . .

2. Adjustments . . . . . . . . . . . . .

3. S15G Screen Layout . . . . . . .

3.1 Adjustment Details . . . . .

3.2 Diagnostic Screen Layout

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.51 .51 .54 .55 .56

S-15G Troubleshooting 1. Troubleshooting Problem Detail .

2. Troubleshooting Tree Detail . . . .

3. Check Engine Light Blink Codes 4. System Fault Codes . . . . . . . . .

5. Effects of Fault Conditions . . . .

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.57 .60 .62 .62 .63

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ii

Vacuum System Diagram and Wiring Schematics 1. Vacuum System Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65 2. S-15G Fuel System Wiring Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 3. ECU Pin Location and Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67 Inspection and Adjustment 1. Periodic Inspection Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68

iii

TYPES OF LP-GAS LP-gases are commercial fuels. They are supplied in liquid form, so that they can be conveniently trans-ported, stored and used. They are mixtures of hydrocarbons, liquefied by pressurization. Though commercially classified as propane LP-gas, butane LP-gas and propanebutane mixture LP-gas, they contain other hydrocarbons (methane, ethane, ethylene, etc.) in small quantities. They are high in calorific value and, as fuel for automotive engines, can take the place of gasoline mainly because of their high octane number.

The simplest one is methane whose basic structure is composed of one carbon atom and four hydrogen atoms (C1H4); it is the first member of the paraffin series. The second is ethane (C2H6); the third, propane. (C3H8); the fourth, butane (C4H10); the fifth, pentane (C5H12), and so on. This series, otherwise called the alkane series, increases the number of hydrogen and carbon atoms according to the general formula CnH2n+2.

The olefin series is another: it starts out with ethylene (C2H4); followed by propylene (C3H6); butylene (C4H8); and so on, the general formula being CnH2n. For use as fuel, olefins are undesirable compounds for the reasons to be stated later.

Hydrocarbons, or compounds of hydrogen (H) with valence of 1 and carbon (C) with valence of 4, are truly many in kind.

STRUCTURE OF ETHYLENE (AN OLEFIN)

STRUCTURE OF METHANE (AN ALKANE)

206353

1. Be sure that the selected LP-gas is satisfactory with respect to vapor pressure*.

Since butane is a major hydrocarbon for LPgas, it may be well to note here that this alkane occurs in two molecular structures: one is normal butane with a boiling point of 0.6 °C (33.1 °F), and the other is isobutane with a b.p. of -10 °C (14.0 °F). Obviously the latter is more volatile.

2. Make sure that the selected LP-gas contains no olefins (unsaturated hydrocarbons) and, if it does, that the percent olefin content does not exceed the prescribed limit.

3. Make sure that the selected LP-gas contains no impurities

Guideline for selecting LP-gas for lifttruck engines

* We have seen that not all LP-gases are fit for use as engine fuel, and that ambient temperature has a great deal to do with LP-gas selection. The rules of thumbs are these:

1

“Vapor pressure” is a function of temperature and may be defined, Ioosely, as the pressure at or below which the liquid can turn to gas where its temperature is given. The v.p. of water at 0 °C (32.0 °F) is 0.5 mmHg (0.020 in.Hg), at 100 °C (212 °F), it is 760 mmHg (29.9 in.Hg) (=1 atm). This means that even a water of 0 °C (32.0 °F) can turn to vapor if the pressure acting on it is reduced to and under 0.5 mmHg (0.020 in.Hg).

TYPES OF LP-GAS Gasoline is volatile, so must be the LP-gas.

The yardstick of volatility is the vapor pressure.

Here resides the reason why the maximum vapor pressure is specified for each grade of LP-gas.

The LP-gas is contained in the supply tank at a pressure sufficiently higher than that of the atmosphere, so that, when its outlet valve is opened, it will flow out by its own pressure: this is one of the reasons why a pump is not used to forward it to the engine. Imagine a tank containing mostly butane and suppose that the tank gets chilled deep to drastically lower the temperature of its LP-gas inside. Then, the inside pressure will fall and the LP-gas might not flow out by its own pressure. Even if the butane came out, it might not turn to gas because its vapor pressure at low temperatures is low. The remedy in such a case is to use a more volatile LP-gas.

is called “addition reaction.” Ethylene molecules can combine to form a larger molecule, polyethylene, through “polymerization reaction.”

Propylene (C3H6) and butylene (C4H8), both olefins, are more reactive than ethylene and, if present in the LP-gas, are likely to form tar-like and rubbery substances and thus foul up the vaporizer, an important device in the LP-gas fuel system. Moreover, they are erosive: eroded diaphragms in the vaporizer are often explained by the presence of these olefins in the LP-gas.

Water and compounds of sulfur or sulfides as impurities can play the serious mischief with metal surfaces in the LP-gas fuel system by their corrosive action and also with the engine exhaust line by giving rise to sulfureous acid gas in the outgoing gases.

LP-gas knock rating and octane number As compared with gasoline, LP-gases are generally high in terms of anti-knock value and hence octane number. An LP-gas of nearly 100% propane is reported to have an octane number of well over 100; the octane number of the 100% butane is reported to range from 97 to 98, a level not far from that of what is sold as “premium gasoline” today.

The octane number of a fuel for the spark-ignition engine is a measure of its anti-knock quality: the higher the octane number, the less is the tendency of the fuel to knock.

Adverse effects of oleflns on LP-gas fuel system Olefins (unsaturated hydrocarbons) are trouble-makers: they are more prone to undergo chemical reactions. Take ethylene, the first and therefore simplest olefin of the series, for example: it can combine with chlorine gas (Cl2) to form ethylene dichloride through what 2

TYPES OF LP-GAS Vapor pressure vs. temperature for mixture of propane and normal butane The statement made earlier to the effect that “vapor pressure” of a liquid is a function of its temperature is graphically illustrated, below, for eleven mixtures of propane and normal butane in varied proportions.

Vapor pressure as gauge pressure MPa (kgf/cm2) [psi]

1.3 (13) [185] Propane C3H8

1.2 (12) [171]

Normal butane

C4H10

1.1 (11) [156]

1.0 (10) [142]

0.9 (9) [128]

0.8 (8) [114]

0.7 (7) [96]

0.6 (6) [85]

0.5 (5) [71]

0.4 (4) [57]

0.3 (3) [43]

0.2 (2) [28]

0.1 (1) [14]

0

-30 (-22)

-20 (-4)

-10 (14)

0 (32)

10 (50)

20 (68)

30 (86)

40 (104)

50 (122)

60 (140)

Temperature °C (°F) 202307

Vapor pressure vs. temperature 3

STRUCTURE AND FUNCTION 1. Outline of LP-gas device 1 5

3

2 4 Hot water

Hot water

Liquid LP-gas Vaporized LP-gas

8 6

7

Air (from air cleaner)

LP-gas + air

1 2 3 4

LP-gas tank LP-gas charge valve LP-gas outlet valve Vacuum fuel lock filter

5 6 7 8

Converter (vaporizer) LP-gas carburetor Vacuum hose LP Thermostat

4

205393A

STRUCTURE AND FUNCTION 2. LP-gas device layout

1

2

9

3

6 10

8

5 4

7 207150

1 LP-gas tank 2 LP-gas charge valve 3 LP-gas outlet valve

4 Vacuum fuel lock filter 5 Converter (vaporizer) 6 LP-gas carburetor

5

7 8 9 10

Hot-water hose Gas outlet hose Tank bracket Relief valve hydrostatic

STRUCTURE AND FUNCTION 3. Main component structures 3.1 LP-gas tank This tank is constructed as shown below. It has a service valve, a sight gauge, an elbow adapter with a raincap, a pressure relief valve, and a fixed liquid level gauge.

The tank is fastened securely to the bracket and needs to be covered to avoid its exposure to direct sunlight. Its fastening bands can be loosened to remove the tank when the engine is serviced.

2

3

1

4

5 206356

206367

“Exact version may vary depending on tank fitted.”

1 Service valve (liquid) 2 Elbow adapter with raincap and pressure relief valve

3 Fixed liquid level gauge 4 Plug (vapor) 5 Sight gauge

3.1.1 Pressure relief valve This relief valve is of fully internal “popaction” type and is located between the elbow adapter and tank body. This valve serves as a primary relief valve and reduces the possibility of foreign material which can prevent proper functioning of the relief mechanism. Its guide, stem and adjusting components are located within the tank — not exposed directly to foreign materials and debris from the atmosphere.

206358

6

STRUCTURE AND FUNCTION 3.1.2 Fixed liquid level gauge Having No. 54 drill size orifice, this gauge is for the LP-gas tank having a dip tube welded in the tank. It is also used where the tank is mounted at the maximum allowable filling level.

206359

3.1.3 Service valve (LP-gas outlet valve) The excess flow check valve located at the inlet consists of a spring, a valve disk complete with a stem, and a nozzle having a seat for the disk.

When the fuel flow rate is normal, the pressure acting on the face of the disk due to fuel velocity is not high, so that the spring keeps the disk pushed off the seat formed of the nozzle.

In the event of an excess flow rate caused, for instance, by failure of a hose connection, the pressure acting on the disk will be so high as to push in the disk against the force of the spring, thereby closing the nozzle to limit the flow of the fuel. This limiting action is due to the equalizing nozzle built in the disk.

The disk pushed against the nozzle will remain seated when a small amount of the fuel is flowing out through the equalizing nozzle but, as the pressure difference across the disk decreases and disappears, the spring will force the disk off to its normal lifted position.

7

206360

STRUCTURE AND FUNCTION 3.1.4 Fuel level indicator Just as the fuel gauge has a float in the gasoline tank, this indicator operates with its float in the LP-Gas tank. As the fuel level in the tank rises or falls, the float also rises or falls. This vertical movement of the float causes the sector shaft to rotate by an amount corresponding to the float movement.

In the head section of the indicator, which is secured to the tank shell, there are two permanent magnets. The one outside of the dial scale carries a needle, and the other is mounted on the end of the drive shaft. These magnets, between which lies a non-magnetic flange, are in such a position that, as the magnet on the drive shaft turns, the magnet on the dial scale turns by the same amount. The scale is calibrated to translate the position of the float into a percentage of the fuel in the tank. Thus, when the fuel level is halfway up, the needle will be at “50” to mean that the tank is 50% full.

6 1 3 5 2 4 206361

4 Float 5 Float rod 6 Counterweight

1 Plexiglas crystal 2 Head 3 Drive shaft

8

PRE CARB SYSTEM STRUCTURE AND FUNCTION 3.2 Filter (Vacuum fuel lock filter) The filter removes impurities contained in liquid LP-gas.

The filter can be removed for cleaning and replacement.

The hose connecting the filter and carburetor supplies negative pressure to the filter.

The valve provided on the filter opens when it receives negative pressure during engine startup, allowing LP-gas to flow.

When the engine is not operating, the lack of negative pressure closes the valve, thus stopping the LP-gas flow.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

1 2 3 4 5 6 8 7

Screw (6) Diaphragm cover Diaphragm Screw (2) Fulcrum Valve operating lever Valve body Retaining washer O-ring lip seal Valve operating pin Valve seat Valve spring Screw (1) Screen Filter Gasket Filter cover Screw (10)

9 10 11 12 13 14 15 16 17 18 205399

9

STRUCTURE AND FUNCTION 3.3 Hydrostatic relief valve The hydrostatic relief valve is a simple spring loaded valve which is normally closed. A hydrostatic relief valve must be present in all fuel transfer lines between shutoffs. The hydrostatic relief valve must have a dust cap covering the outlet to prevent contamination of the valve.

The purpose of the hydrostatic relief valve is to protect the fuel transfer line from over pressure of not less than 400 psi/2.8 mPa and not more than 500 psi/3.5 mPa. When the pressure in the fuel transfer line exceeds the operating pressure of the hydrostatic relief valve, the valve is forced off of it’s seat allowing LPG to escape thus reducing the pressure in the fuel transfer line. When the pressure drops below the opening pressure of the hydrostatic relief valve, the valve closes.

10

PRE CARB SYSTEM STRUCTURE AND FUNCTION 3.4 Converter (vaporizer) and LP-gas carburetor 3.4.1 Converter (vaporizer) This converter is a water-heated, two-stage vaporizer. Fuel enters the converter at tank pressure as a liquid and its pressure is reduced to 9.8 to 14.7 kPa (0.1 to 0.15 kgf/cm2) [1.4 to 2.1 psi] within the primary or vaporizing chamber where it is converted from liquid to a gas.

Heat for vaporization is supplied from the engine cooling system.

3.4.2 LP-gas carburetor The LP-gas carburetor is a mixing valve that mixes the vaporized fuel and air. The gas metering valve is connected directly to the air valve so that the accurate gas-air ratios are maintained.

The purpose of the idle fuel mixture adjustment screw is to adjust the gas-air ratio for idling run of the engine. The power fuel mixture adjustment valve controls the gas flow through the LP-gas carburetor when the engine is loaded.

Gas then passes through the secondary valve which is controlled by the secondary diaphragm and flows into the secondary chamber where it is drawn off through the gas outlet to the LP-gas carburetor.

Liquid LP-gas

Primary seat Primary chamber LPgas pressure: 9.8 kPa (0.1 kgf/cm2) [1.4 psi]

Converter

Secondary diaphragm Water chamber Manual primer Atmospheric vent Secondary seat

Atmospheric vent

Air valve spring Air valve

Diaphragm

Secondary chamber

Primary diaphragm

Vaporized LP-gas Air (from air cleaner)

Idle fuel mixture adjustment screw

Power fuel mixture adjustment valve Idle fuel mixture adjustment valve

Power fuel mixture adjustment valve

Gas + air LP-gas carburetor 205397

11

ACTIONS TO BE TAKEN IN THE EVENT OF A FAILURE (1) When you smell the gas or notice something wrong with the LP-gas equipment during operation, immediately stop the lift truck in a safe area, turn the starter switch to “OFF” position, close the service valve (RED) of LP-gas tank, and try to find the cause. (It is advisable to have a test kit on hand for detecting gas leakage in the event of the failure.)

(2) If the internal pressure of LP-gas tank rises too high for one reason or another to cause the safety valve to open and let out the excess pressure, sprinkle water over the tank and, at the same time, extinguish the fire burning near the lift truck, if any, and ventilate the working area to rarefy the leakage gas.

(3) When gas leakage is evident, extinguish the fire burning near by and close the service valve (RED) of the tank as soon as possible.

(4) If there is a possibility of fire in the event of collision or overturning of the lift truck, close the service valve (RED) of the tank as soon as possible.

(5) The LP-gas tank installed in correct position will not explode even if it is in a blaze.

What to do in the event of emergency is to remove inflammable material from around the tank quickly.

(6) Use a dry-chemical (powder) type or carbon dioxide type extinguisher. Never use water. It is a good practice, however to sprinkle a large quantity of water over the LP-gas tank for cooling it down while extinguishing the fire.

(7) Only trained and authorized personnel should fill or exchange LP-gas tanks.

(8) Personnel engaged in filling of LP-gas tanks should wear protective clothing such as a face shield, long sleeves and gauntlet gloves.

(9) Do not refuel or store LP-gas powered lift trucks near any underground entrances, elevator shafts, or any other place where LP-gas could collect in a pocket causing a potentially dangerous condition.

(10) Do not leave the lift truck, for even a short period of time, in the vicinity of objects with high temperatures, such as ovens and furnaces. The heat may raise the pressure of the fuel and open the relief valve.

(11) Close the service valve on the tank when LP-gas fueled lift trucks are parked overnight or stored for a long period of time indoors with the fuel tank in place.

(12) Close the valves on empty tanks.

(13) Examine all LP-gas tanks before filling again before reuse, for damage to the valves, liquid gauge, fitting and hand wheels.

(14) Check for dents, scrapes or other damage to the pressure vessel and for dirt or debris in the openings.

(15) All defective or damaged LP-gas tanks must be removed from service.

(16) The careless handling of LP-gas tanks can result in a serious accident. Extreme care should be exercised when transporting tanks so that the tanks are not damaged.

(17) The storage and handling of liquid fuels in the U.S.A., should be in accordance with the NFPA No.30, “Flammable and Combustion Code.” Outside the U.S.A. store and handle in accordance with local regulations.

(18) The lift truck should be refueled only at designated safe locations. Safe outdoor locations are preferable to those indoors.

12

ACTIONS TO BE TAKEN IN THE EVENT OF A FAILURE (19) DO not completely fill the tank. The fuel expands when it gets warm and it may overflow. This will create a fire hazard.

(20) Only trained and authorized personnel should fill or exchange LP-gas tanks.

(21) Do not drop, throw, roll or drag LP-gas tanks. Do not strike LP-gas tanks or any associated parts of the tanks or fuel systems.

(22) Check the LP-gas tank for secure mount ing. Loose tanks can cause pressure fuel lines to leak, resulting in personal injury.

(23) Carefully read the caution labels.

(MCFA only)

“FUEL GAUGE” DECAL

“MAINTENANCE” DECAL

“L.P.G.” DECAL

“FUEL” DECAL 207151

13

PRE CARB TROUBLESHOOTING Engine does not start even though there is no equipment abnormality.

No LP-gas in tank

Refill LP-gas tank.

Be sure to open gas outlet valve on LP-gas tank.

Improper operating procedure

Do no use choke.

Do not press accelerator pedal all the way.

Overactivation of excess flow valve in gas outlet valve on LPgas tank

Close gas outlet valve (red handle) on LP-gas tank, and leave in that condition for about 1 minute. When gas pressure stabilizes and valve deactivates, open gas outlet valve.

Clogged filter

Disassemble and clean filter.

Difficulty in starting or failure to start

No LP-gas is supplied to converter.

Replace filter and screen.

Engine starts immediately.

but

Improper idle speed adjustment

Adjust idle fuel mixture adjustment screw on LP-gas carburetor.

Excessively low cooling water temperature

Use coolant.

Check for clogs in cooling water hoses and thermostat damage.

Insufficient gas pressure due to low temperature

If LP-gas tank pressure is lower than 98 kPa (1 kgf/cm2) [14.2 psi], increase propane content of LP-gas. (Ambient temperature: 0°C (32°F))

Malfunction of LP-gas carburetor

Check for sticking of air valve.

stalls

Others

If air valve sealing ring is worn, replace.

Mixing of air due to faulty connection of air hose to LP-gas carburetor

14

Use hose clamp to tighten the connection.

PRE CARB TROUBLESHOOTING

Faulty idling operation

Engine operation stops or is unstable at idle speed, or idle speed is too high.

Poor engine performance or stalling of engine

Others

Engine power decreases gradually during operation, and engine speed does not increase.

Engine stalls a short time after startup.

Strong gas smell

Improper setting of idle fuel mixture adjustment screw on LP-gas carburetor

Make adjustment.

Accumulation of rubber particles, oil and metal particles inside converter

Disassemble and clean.

Torn diaphragm in converter

Replace diaphragm.

Faulty secondary valve seat in converter

If valve does not completely rest on seat, replace seat.

Primary pressure exceeding 14.7 kPa (0.15 kgf/cm2) [2.1 psi] and, causing rich fuel mixture. (Damaged primary valve seat)

Replace primary valve seat.

No LP-gas

Refill with LP-gas. Exchange LP-gas tank.

Freezing of converter Hot water (engine cooling water) temperature is too low, or insufficient LP-gas

Remove hot-water hose at outlet to check if hot water is properly circulating (clogged hose).

Gas leaks from damaged LP-gas hose

Repair damaged hose.

Torn primary diaphragm in converter

Stop operation immediately, and replace primary diaphragm.

15

Poor acceleration

PRE CARB TROUBLESHOOTING Damaged primary valve seat in converter

Replace primary valve seat.

Improper adjustment of power fuel mixture adjustment valve on LP-gas carburetor

Adjust power fuel mixture adjustment valve until appropriate acceleration performance is achieved.

Internal contamination of converter

Disassemble converter and clean internal parts.

Torn secondary diaphragm in converter

Replace diaphragm.

Power fuel mixture adjustment valve opening too large

Turn power fuel mixture adjustment valve slightly to (L) side.

Torn primary diaphragm in converter

Replace diaphragm.

Excessive tightening of power fuel mixture adjustment valve

Adjust power fuel mixture adjustment valve by turning to (R) side.

Internal contamination of converter

Disassemble converter and clean internal parts.

Torn secondary diaphragm in converter.

Replace diaphragm.

Leaks in hose

Repair leaks.

Torn primary valve seat

Replace primary valve seat.

Insufficient power (gas mixture too rich or too lean)

Adjust power fuel mixture adjustment valve.

Insufficient power

Excessive gas

Excessive fuel consumption

Insufficient gas

Strong gas smell

Others

16

PRE CARB DISASSEMBLY AND REASSEMBLY 1. Main components of LP-gas device (4G63, 4G64) Disassembly 3

9 4

11 7 8 12 6 10

5 1

2

Hoses and other minor specifications are different for MCFE. 207152A

Disassembly sequence 1 Hot-water hose 2 Hot-water hose 3 Pipe 4 LP-gas hose 5 LP-gas hose 6 Vacuum hose

7 8 9 10 11 12

17

Vacuum hose LP-gas converter Filter Air hose Carburetor Thermostat

DISASSEMBLY AND REASSEMBLY 2. Main components of LP-gas device (6G72) Disassembly

12

4 3

13 8

7

6

5 10

11 1

2

9

10

207417

Disassembly sequence 1 Hot-water hose 2 Hot-water hose 3 Pipe 4 LP-gas hose 5 LP-gas hose 6 Vacuum hose

7 8 9 10 11 12 13 18

LP-gas converter Filter Air hose Blow-by hose Carburetor Hydrostatic relief valve LP-Gas hose to LPG tank

PRE CARB DISASSEMBLY AND REASSEMBLY 3. Disassembly and reassembly of LP-gas carburetor/ mixer (CAIOO) * COMPONENTS INCLUDED IN THE REPAIR KIT. DISASSEMBLY AND REASSEMBLY (1) Remove the air valve cover and retaining screw. Place a chalk mark on the air valve diaphragm and the mixer body. This mark will allow correct positioning during reassembly.

1 2

(2) Lift out and replace the air valve assembly in the mixer body.

3 4

(3) Press the air valve down until it bottoms into the body.

5

(4) Align the chalk mark on the air valve diaphragm with the chalk mark on the mixer body. Reassemble the air valve cover and install retaining screws.

6

* 7 8

13 10 12 11

9

14 15

14

16

205403

19

DISASSEMBLY AND REASSEMBLY (1) Remove the air valve cover and retaining screw. Place a chalk mark on the air valve diaphragm and the mixer body. This mark will allow correct positioning during reassembly.

Chalk mark

205404

(2) Lift out and replace the air valve assembly in the mixer body.

205405

(3) Press the air valve down until it bottoms into the body.

205406

(4) Align the chalk mark on the air valve diaphragm with the chalk mark on the mixer body. Reassemble the air valve cover and install retaining screws.

205407

20

PRE CARB DISASSEMBLY AND REASSEMBLY 4. Disassembly and reassembly of converter/ regulator (J) (vaporizer)

* COMPONENTS INCLUDED IN THE REPAIR KIT.

Disassembly 1 Disassembly sequence 1 Screw (6) 2 Secondary cover 3 Secondary diaphragm 4 Screw (1) 5 Secondary seat lever 6 Secondary seat Secondary seat pin 7 Fulcrum pin 8 Spring 9 Screw (7) 10 Primary cover 11 Primary diaphragm 12 Primary valve pin 13 Spring 14 Cover plate 15 Gasket 16 Primary valve seat 17 Converter body

2 3 4 5 6 7 8 17 ✱

16 15 14

Note

(1) Parts indicated with an asterisk (✱) are included in the repair kit.

(2) When converter is disassembled, be sure to replace gasket 15 with a new one during reassembly.

13 12 11 10 9 205132

(1) Repair kit contains all necessary replacement parts to replace components subject to deterioration. All components in the repair kit should be used when overhauling converter or when converter has not been used for an extended period of time.

Converter gaskets and diaphragms deteriorate if converter is stored for a prolonged period after being used.

21

DISASSEMBLY AND REASSEMBLY (2) Start disassembly by removing secondary cover. Take out six screws, and tap the perimeter of the cover with the plastic handle of a screwdriver to loosen secondary cover from its mounting position.

206713

(3) Remove secondary diaphragm.

Slide secondary diaphragm toward gas inlet side to disengage diaphragm link from secondary seat lever.

206714

(4) At this stage, secondary seat lever is still positioned in link slot. Move secondary diaphragm to clear the slot.

206715

(5) Remove screw, and dismount secondary seat lever, secondary seat, secondary seat pin, fulcrum pin and spring from converter body.

Note that locating tabs for spring are provided on both sides of lever. These tabs, together with the tab on the top of lever, retain the spring in proper position and prevent it from slipping out of place.

206716

22

DISASSEMBLY AND REASSEMBLY (6) Take out seven screws, and remove primary cover and primary diaphragm.

Note rectangular lever riveted to primary diaphragm. This lever is supported on the upper side by a fulcrum cast in the cover.

The lever rocks on the fulcrum to depress primary valve pin and spring. In illustration, the pencil points to pressure sensing port.

206717

(7) Primary valve is operated by primary valve pin that moves through a boss in the cover plate of converter body. This prevents diaphragm from contacting LP-gas, thus preventing diaphragm stiffening caused by refrigeration.

206718

(8) Illustration on the right shows converter with cover plate and gasket removed.

Located inside the body are serrated vaporizing chamber and heat exchange circuit which heats vaporized LP-gas.

206719

(9) In illustration, the pencil points to aluminum alloy backing of primary valve in vaporizing chamber.

Viton sheet is bonded to this backing.

(10) Remove gasket from cover plate of converter body.

206720

23

DISASSEMBLY AND REASSEMBLY Reassembly (1) Take out parts from the repair kit.

Secondary diaphragm (1) Secondary seat (1) Secondary seat pin (1) Gasket (1) Primary valve pin (1) Primary diaphragm (1)

(2) Position gasket and cover plate of converter in place, and mount primary valve pin and spring.

206721

(3) Position primary cover, diaphragm and converter body cover plate in place, and tighten seven screws until they contact the cover. Then, tighten screws in a diagonal sequence until all screws are tightened evenly.

Note: Primary cover has marks that indicate positions of gas inlet, hot water inlet and outlet, and primary pressure check plug. Orifice located below the bottom mark is a vent for primary diaphragm.

206722

(4) Bend or straighten old secondary seat pin and remove secondary seat (right).

Replace with new secondary seat and secondary seat pin.

206723

24

DISASSEMBLY AND REASSEMBLY (5) Draw pin through secondary seat lever.

Pull the pin until the head of the pin contacts seat, but leave it loose enough so that seat can tilt to allow alignment with secondary jet.

206724

(6) Bend pin and hold seat in place.

Cut off excess part of the pin.

206725

(7) Install spring, and mount secondary seat lever with screw.

206726

(8) When installing secondary seat lever, insert secondary seat lever and fulcrum pin into the locating groove, and tighten screw to secure the parts in place.

206727

25

DISASSEMBLY AND REASSEMBLY (9) Align diaphragm link slot to the end section of secondary seat lever.

Gap from which link is punched should face gas inlet.

Refer to steps (3) and (4) of the disassembly procedure.

206728

(10) Position secondary diaphragm in place, and mount secondary cover with six screws.

Tighten screws until they contact secondary cover. Then, tighten screws from one side to the other until all screws are tightened evenly.

CAUTION

Use only brass fittings in the hot water inlet and outlet passages. Steel fittings cause casting to deteriorate due to electrolysis.

206729

CAUTION

After assembly in complete, conduct a pressure test using a soapy solution or testing solution to make sure there is no leak.

26

PRE CARB DISASSEMBLY AND REASSEMBLY 5. Disassembly and reassembly of LP-gas filter, fuel lock (VFF30)

CAUTION 1. DO NOT use Teflon thread tape on any of the NPT pipe-thread fittings where fuel travels. Use a suitable fuel resistant joint compound.

2. Be sure to leak-check all fittings and covers for fuel tanks, using a soapy solution.

3. Be sure to use proper mounting bolts to secure the lockoff. Bolts which are too long may cause severe damage to the lockoff.

Disassembly * COMPONENTS INCLUDED IN THE REPAIR KIT.

Disassembly sequence 1 Screw (10) 2 Filter cover 3 Gasket 4 Filter 5 Screen 6 Screw (1) 7 Valve spring 8 Valve seat 9 Valve operating pin 10 Retaining washer 11 O-ring lip seal 12 Screw (6) 13 Diaphragm cover 14 Diaphragm 15 Screw (2) 16 Fulcrum 17 Valve operating lever 18 Valve body

12 13 14 15 16 17 10

✱

18 11 9 8 7 6 5 4 3 2 1 205399

27

DISASSEMBLY AND REASSEMBLY (1) Take out ten screws, and remove filter cover and gasket.

206730

(2) Remove filter and screen.

206731

(3) Take out screw, and remove valve spring.

206732

(4) Remove valve seat and valve operating pin.

206733

28

DISASSEMBLY AND REASSEMBLY (5) Diagram on the right shows the relationship of valve spring, valve seat, valve operating pin, seat retaining washer and O-ring.

When valve operating pin is removed, seat retaining washer can be taken out through the “Fuel Out” opening.

206734

(6) Insert wire through the “Fuel Out” jet hole, hook the wire on retaining washer, then pull it out.

206735

(7) Using the same wire, take out O-ring lip seal through the hole from which valve operating pin is removed in step (4).

Wash body, cover and jet as needed, using kerosene or cleaning oil. Do not use carburetor cleaner since it erodes synthetic rubber seals.

206736

(8) Take out six screws on diaphragm side, and remove diaphragm cover and diaphragm.

Wash parts as needed, using kerosene or cleaning oil.

Do not remove fulcrum or valve activating lever on diaphragm side.

206737

29

DISASSEMBLY AND REASSEMBLY Reassembly (1) Seat holder (H1-14236) should be positioned as shown in illustration (bottom tool).

Note that the hole in which the O-ring lip seal is installed is tapered, and that the wider end of the opening faces up.

Replacement seal must be coated with silicone grease before it is inserted into holder.

Place greased O-ring lip seal into the holder using installation pin (P1-14235), and re-coat seal with silicone grease.

The seal must be in the position shown in illustration, with groove facing up and visible. Seal is tapered to match the hole in the holder.

Note

INSTALLATION PIN

SEAT HOLDER

206738

“H1-14236” and “P1-14235” are special tool numbers of Impco Company.

(2) With O-ring lip seal in the holder, groove visible and facing up, slide holder (with Oring lip seal) into the body.

Look through the fuel hole to check positioning of the seal. The seal must be positioned above the cavity of the seal recess.

Coat installation pin with silicone grease, and push seal through holder and into the seal recess of the body.

Remove installation pin, and look through the fuel hole to check for proper installation.

The seal should be seated in the seal recess, and groove should be visible.

206739

(3) Use needle nose pliers to install retaining washer through the “Fuel Out” opening.

Refer to the cross-sectional diagram for step (5) of the disassembly procedure.

206740

30

DISASSEMBLY AND REASSEMBLY (4) Coat valve operating pin with silicone grease, and insert in the body, so that pin passes through retaining washer and Oring lip seal. Rotate pin slowly to ease passage through washer and O-ring.

206741

(5) Place valve seat on top of the head of operating pin, with aluminum side facing up.

Make sure that Viton side is positioned towards the head of the pin.

206742

(6) Mount valve spring with screw. Lift valve spring slightly to confirm its freedom of movement.

206743

(7) Install screen and filter, place gasket, then mount filter cover with screws.

206744

31

DISASSEMBLY AND REASSEMBLY (8) Reassembly of diaphragm side Check valve operating lever for freedom of movement.

Use silicone grease to coat the surface of the gasket that contacts the body. Note that holes align only when the gasket is installed correctly.

Rivet heads on diaphragm should be on the cover side, not the body side.

206745

(9) Install diaphragm to the body, and mount diaphragm cover with screws.

Tighten screws evenly.

206746

32

PRE CARB INSPECTION AND ADJUSTMENT 1. LP-gas tank inspection Disassembly of components that are subject to high pressure, such as container, valve, level indicator device, must be performed by persons legally qualified and in shops certified under regulations. Request a certified shop to inspect the LP-gas tank.

2. Filter inspection (1) Parts replacement after filter disassembly With the parts contained in the repair kit, replace the filter, screen, gasket and other parts.

(2) Tighten the cover securely during the reassembly process.

After reassembly, check to make sure that there is no gas leak.

1 2 3 4 5 6 8

* Components included in the Repair Kit. 1 Screw 3 Diaphragm 8 Retaining washer 9 O-ring lip seal 10 Valve operating pin 11 Valve seat 14 Screen 15 Filter 16 Gasket 18 Screw

✱

7 9 10 11 12 13 14 15 16 17 18 205399

33

INSPECTION AND ADJUSTMENT 3. Converter (vaporizer) inspection and adjustment (1) Hot-water hose inspection The converter uses heat supplied by the engine cooling water to vaporize fuel.

Inspect the hot-water hoses for damage.

(2) Bleeding converter If hot water does not circulate properly, bleed the converter to remove air trapped in the water core.

To bleed the converter, remove the air vent plug on the side of the converter, and let the engine idle.

After making sure that intermittent flows of coolant with air from the plug hole have changed to a smooth flow, install the plug.

(Apply ThreeBond No. 1142 or equivalent sealant on plug threads.)

AIR VENT PLUG

205134

(3) Primary chamber pressure measurement Remove the plug located on the back side of the converter. Mount an R (PT) 1/4 connector and a pressure gauge to the pressure measuring port. Operate the engine with LP-gas. If the pressure indication shows a value from 9.8 to 14.7 kPa (0.1 to 0.15 kgf/cm2) [1.4 to 2.1 psi], it is normal.

If the pressure is less than 9.8 kPa (0.1 kgf/cm2) [1.4 psi], the engine lacks power on an upgrade inclination. If the pressure is higher than 14.7 kPa (0.15 kgf/cm2) [2.1 psi], the engine produces high output power but fuel consumption increases.

If the measured pressure is outside the specified range, disassemble the converter and replace the secondary seat.

REMOVE PLUG

205135

34

INSPECTION AND ADJUSTMENT 4. Idle speed adjustment After sufficient engine warm-up operation, adjust the idle fuel mixture adjustment screw of the LP-gas carburetor so that the engine idles at 650 to 700 rpm.

(1) Connect a tachometer.

Connect the positive (+) lead wire of the tachometer to the negative (-) terminal of the ignition coil, and the negative (-) lead wire to the vehicle chassis.

IGNITION COIL

202327

(2) Let engine idle.

(3) Turn the idle fuel mixture adjustment screw of the LP-gas carburetor to the right until the engine operation becomes most stable.

Idle fuel mixture adjustment screw Open (turn to the left)

Fuel mixture condition

Engine condition

Lean

Unstable idling

Close (turn clockwise)

Rich

High fuel consumption (Increases CO discharge and LP-gas smell)

PRELIMINARY POWER VALVE SETTING

205398

ENGINE

TIMING BTDC

LOW IDLE RPM %CO

STALL RPM %CO

4G63

9° ± 1°

4G63 Optional 4G64

@ 650˜

1920 ± 100

4G64

700 RPM

1920 ± 100

4G63

9° ± 1°

2080 ± 100

4G63 Optional 4G64

@ 650˜

1910 ± 100

4G64

700 RPM

1910 ± 100

6G72

9° ± 1° @ 650˜ 700 RPM

HIGH IDLE RPM %CO

2070 ± 100 650 ˜ 700

650 ˜ 700

0.2 ˜ 0.8%

0.2 ˜ 0.8%

1740 ± 100 0.3 ˜ 0.8%

1730 ± 100 0.3 ˜ 0.8%

2550 ˜ 2700

0.8% MAX.

2550 ˜ 2700

0.8% MAX.

650 ˜ 700 0.05 ˜ 0.25% 1800 ± 100 0.4 ˜ 0.9% 2550 ˜ 2600

35

0.9% MAX.

INSPECTION AND ADJUSTMENT 5. Output power adjustment Set the power fuel mixture adjustment valve as shown below.

(1) If the power fuel mixture adjustment valve is turned toward “L” side, the power mixture becomes lean, resulting in lack of power.

(2) If the power fuel mixture adjustment valve is turned toward the “R” side, the power mixture becomes rich, resulting in excessive exhaust gases and CO and lack of power.

Power fuel mixture adjustment valve

205398A

6. Gas leak check procedure (1) Open the gas outlet valve on the LP-gas tank.

(2) Turn the starter switch to the START position to start the engine.

(3) Use a gas leak tester or soapy solution to check the pipe joints for leaks.

36

STRUCTURE AND FUNCTION

CARB T ier 1 Emissions C ontrol S ystem The California Air the state’s state’s environThe California AirResources Resources Board Board (CARB) (CARB) is is the mental regulatory agency. agency.

CARB has issued emissions regulations environmental regulatory CARB has issued emissions for certain types of industrial not already covered regulations for certain typesequipment of industrial equipment not by existalready by existing EPAregulation regulations.

This new regu- using ing EPAcovered regulations.

This new impacts vehicles lation impacts vehicles using “large “large spark-ignited” engines above spark-ignited” 25 horsepower,engines including lift above 25 horsepower, including lift trucks.

The term “sparktrucks.

The term “sparkignited” includes all engines using gasoline, ignited” includes all engines using gasoline, LP, and related LP, and related fuel types, such as Compressed Natural Gas. The fuel types, applies such asonly Compressed Natural Gas. The regulation regulation to new equipment, starting with units proapplies only to new equipment, starting with units produced duced in year 2001, and does not require existing equipment to be in year 2001, and does not require existing equipment to be modified to meet the new emissions standards. modified to meet the new emissions standards.

The CARB regulations regulations require require lift lift truck The CARB truck manufacturers manufacturerstotomodify a percentage of the trucks sold into California, in year 2001, modify a percentage of the trucks sold intobeginning California, to incorporate an emissions control system (ECS) which will achieve beginning in year 2001, to incorporate an emissions control system (ECS) whichlevels will achieve emissions levels exhaust emissions defined exhaust within the regulations.

In the foldefinedyears, within regulations.

In thesold following years, the lowing thethe percentage of trucks with emissions reduction percentage of trucks sold with emissions reduction technology technology must increase each year until 2004, when the entire must increaseengine each year when thecompliant. entire sparksparkignited line until must 2004, be emissions This initial ignited engine line must be emissions compliant.

This initial phase-in period is designated “Tier 1”, and defines exhaust emisphase-in period which is designated 1”, and defines exhaust at the sions standards must be “Tier achieved by the manufacturer emissions standards which“Tier must achievedwill by take the manutime of shipment.

In 2004, 2” be regulations effect, with a facturer at the time of shipment. In 2004, “Tier 2” regulations proposal by the EPA to adopt this as a nationally-legislated standard. will take effect, with a proposal by the EPA to adopt this as a The emissions standards and phase-in percentages are and shown in nationally-legislated standard.

The emissions standards the chart below. phase-in percentages are shown in the chart below.

Effective Date Emissions Limits CO (g/hp-hr) HC + NOx Useful Life / Durability Testing Emissions Limits (g/hp-hr)

Tier 1 CARB

Tier 2 CARB

Jan 2001 to Dec 2003 37 3

Jan 2004 to Dec 2006 37 3 3500hr/5yr 50 CO 4 HC + NOx

N/A

Warranty Period- Components

Phase-In % Production Line Testing In-Use Testing System Adjustment Tampering

< $400 > $400 2001 2002 2003

1500hr / 2yr 1500hr / 2yr 25% CA Sales 50% CA Sales 75% CA Sales Required N/A Resistant

37

2500hr / 3yr 3500hr / 5yr 100% USA Required Required Tamper-Proof

STRUCTURE AND FUNCTION

1. Outline of CARB Tier 1 LP-gas system

Function of components

38

STRUCTURE AND FUNCTION 2. CARB Tier 1 LP-gas layout (2001-2002 Model Year)

Mixer Throttle Body LP Filter

FCSV

Fuel Lock 0ff Vaporizer

Location of components on truck

CARB Label

39

STRUCTURE AND FUNCTION 3. Main Component Illustrations 3.1 Electronic Control Unit (ECU) Identification of ECU is shown in examples below

version 1

version 2

3.2. Electronic Control Unit (ECU)

40

STRUCTURE AND FUNCTION 3.3. Oxygen sensor mounted in exhaust manifold

3.4. Pedal Sensor

3.5 Engine Block Temperature Sensor

41

STRUCTURE AND FUNCTION 3.6. Mixer and Throttle Body Illustration LP GAS VALVE CARBURETOR INTERNAL GAS FLOW PART LOAD METERING VALVE NON ADJUSTABLE Pressure Transfer holes Metering Spring Diaphragm FCSV Air Measuring Valve Fuel Metering Valve LP Gas (Vapor) From Regulator

Air

IDLE AIR ORIFICE NON ADJUSTABLE

Vacuum Advance Port

Map Electronic Throttle body

3.7. Three Way Catalytic Converter

42

STRUCTURE AND FUNCTION 3.8 Dash Light Illustration

Transmission Fluid level Low Oil Charging System Oil Temp Brake Pressure

43

Check Engine

STRUCTURE AND FUNCTION 3.9. Exploded view for use with Pneumatic type models

1 2 3 4

LPG Converter Fuel Lock Filter Fuel Control Solenoid Valve ECU

5 6 7 8 44

Mixer Oxygen Sensor Throttle Body Vacuum Lines

STRUCTURE AND FUNCTION 3.10 Exploded view for use with cushion type models

1 2 3 4

LPG Converter Vacuum Lines Fuel Lock Filter Fuel Control Solenoid Valve

5 6 7 8 45

ECU Throttle Body Mixer Oxygen Sensor

STRUCTURE AND FUNCTION 2. Terminology Engine management systems use a variety of acronyms and system specific terms. The following list of terms and acronyms are used in the CARB 1 Tier 1 system. (Reference SAE J1330 terminology.)

Systems Operation 1. Explanation of Operation 4G63 (2.0 L.) & 4G64 (2.4 L.) LPG closed loop fuel control system with 3 way catalyst.

Regulatory Background: MCFA has developed an emissions-compliant control system. The control system is a closedloop system with a 3-way catalytic converter as standard. It utilizes electronic fuel delivery with "drive-by-wire" throttle and governor control. The key system component is the Electronic Control Unit (ECU) that monitors various sensors on the truck, and controls engine performance to pre-programmed specifications. The two main sub-systems are: • Fuel control • Throttle and governor control The benefit to the user is a vast improvement in indoor air quality, engine drivability and performance, maintenance and fuel economy.

A/F BAT CAT ECU EGO ET

Air Fuel Mixture Battery Voltage Catalytic Converter Electric Control Unit Exhaust Gas Oxygen Sensor Engine Temperature (Engine block temp.)

FCSV Fuel Control Solenoid Valve MAP Manifold Absolute Pressure OXY Oxygen RPM Engine Revolutions per Min. SFL System Fault Light SFC System Fault Code

Sub-system Operating Principles 1. Fuel Control: The fuel control system utilizes a "closed loop" fuel control strategy. The "Closed loop" method is used to calculate the correct air and fuel mixture ratio (A/F) based on ECU programming using data collected from sensor inputs while the engine is operating. This sub-system monitors four engine parameters and transmits this information to the ECU. The ECU is able to adjust the fuel supply by varying the output to the fuel control solenoid valve (FCSV). The inputs and output for this subsystem are as follows: 1) Engine manifold pressure (MAP) is an indicator of engine load. Higher loads result in a numerically higher MAP value.

2) Engine speed to indicate current engine revolutions per minute (RPM)

46

STRUCTURE AND FUNCTION 2. Terminology Engine management systems use a variety of acronyms and system specific terms. The following list of terms and acronyms are used in the CARB 1 Tier 1 system. (Reference SAE J1330 terminology.)

Systems Operation 1. Explanation of Operation 4G63 (2.0 L.) & 4G64 (2.4 L.) LPG closed loop fuel control system with 3 way catalyst.

Regulatory Background: MCFA has developed an emissions-compliant control system. The control system is a closedloop system with a 3-way catalytic converter as standard. It utilizes electronic fuel delivery with "drive-by-wire" throttle and governor control. The key system component is the Electronic Control Unit (ECU) that monitors various sensors on the truck, and controls engine performance to pre-programmed specifications. The two main sub-systems are: • Fuel control • Throttle and governor control The benefit to the user is a vast improvement in indoor air quality, engine drivability and performance, maintenance and fuel economy.

A/F BAT CAT ECU EGO ET

Air Fuel Mixture Battery Voltage Catalytic Converter Electric Control Unit Exhaust Gas Oxygen Sensor Engine Temperature (Engine block temp.)

FCSV Fuel Control Solenoid Valve MAP Manifold Absolute Pressure OXY Oxygen RPM Engine Revolutions per Min. SFL System Fault Light SFC System Fault Code

Sub-system Operating Principles 1. Fuel Control: The fuel control system utilizes a "closed loop" fuel control strategy. The "Closed loop" method is used to calculate the correct air and fuel mixture ratio (A/F) based on ECU programming using data collected from sensor inputs while the engine is operating. This sub-system monitors four engine parameters and transmits this information to the ECU. The ECU is able to adjust the fuel supply by varying the output to the fuel control solenoid valve (FCSV). The inputs and output for this subsystem are as follows: 1) Engine manifold pressure (MAP) is an indicator of engine load. Higher loads result in a numerically higher MAP value.

2) Engine speed to indicate current engine revolutions per minute (RPM)

46

STRUCTURE AND FUNCTION 3)

4)

Oxygen sensor mounted in the exhaust manifold. This sensor produces a voltage, based on the oxygen content of the exhaust stream, to indicate the current A/F. Engine temperature to indicate the fuel requirements for cold starting, general operation, and as a monitor of proper engine functional condition.

Note: These parameters can be monitored during engine operation using the diagnostic tools, as described in the troubleshooting section.

INPUT (To ECU) MAP (Manifold Absolute Pressure) RPM (Engine RPM) OXY (Oxygen Sensor Voltage) ET (Engine Block Temperature)

OUTPUT (From ECU) FCSV (Fuel Control Solenoid Valve)

Note: See Wiring Schematic section for wiring locations and wire colors.

47

STRUCTURE AND FUNCTION 2. Fuel Control Operation: When the operator turns the key to start the engine, the ECU power supply is activated.

After the engine starts the distributor provides a signal to the ECU by a connection in the wiring harness that provides the current RPM. Once the ECU detects a RPM, a ground circuit is activated to the electronic LP lock off, to "open" the valve and allows the LP gas to begin flowing. The electronic LP lock off is normally closed when the engine is not running.

Upon start-up the ECU monitors for engine temperature and will adjust the air-fuel control valve rich to compensate for the cold engine.

The idle RPM is increased (over the base idle set speed of 700RPM) during the warm-up period. During the warm-up period, the A/F ratio is determined by presets in the ECU and not influenced by the oxygen sensor. This is called “Open Loop mode”. The engine will NOT operate in "closed loop" fuel control until the following conditions have occurred.

1) Engine must be warmed to operating temperature.

2) The operator must have applied accelerator input causing the engine RPMs to exceed 2000 RPMs for a brief period of time.

Once the engine is operating in closed loop mode, the ECU will begin to actively adjust the fuel flow to keep the A/F ratio at stoichiometric.

Stoichiometric is the A/F ratio that allows maximum combustion efficiency and allows the catalytic converter to minimize the exhaust pollutants. If the A/F ratio is not kept at stoichiometic, the catalyst will not operate correctly. If the ECU detects that the closed loop control system is not operating correctly and the A/F ratio is not in the normal range for longer than 90 continuous seconds, the check engine light will illuminate and a "limp home" feature is activated and the maximum engine RPM is limited to 1800. If the engine is operated at high RPMs and high hydraulic use or intense driving demands while the closed loop fuel control system is not operating properly, damage to 48

the catalyst may result. When the ignition switch is turned off, the error recorded by the ECU is reset. The S-15G ECU does not store error codes. Upon restart, the engine will operate normally unless an error is again detected.

Periodic illumination of the check engine light does not necessarily indicate a fuel control system malfunction. Poor fuel quality, improper system operation and running an LP tank dry can also cause a "closed loop" error which will be displayed on the diagnostic monitors as an "OXY" code.

By monitoring changes in MAP and RPM the ECU can determine the engine load, if the engine is accelerating or decelerating the ECU will calculate a suitable increase or decrease in A/F to match the engine condition. The fuel flow is controlled by the Fuel Control Solenoid Valve (FCSV). The FCSV is a 12 volt electrically operated solenoid valve that is inline between the vacuum port on the mixer and the regulator converter assembly. The FCSV is normally in the closed position when no voltage is provided.

The mixer, the FCSV, and the regulator are connected by a network of vacuum lines. The FCSV operates at specific "DWELL" based on fuel requirements. A 50% dwell means the valve is open 50% of the time and closed 50% of the time. A DWELL of 100% indicates that the valve is open 100% of the time and the fuel control system is at full "lean". A DWELL of 0% indicates that the valve is closed 100% of the time and the fuel control system is full "rich". Normally, the FCSV will operate at a DWELL between 20-80 depending on local atmospheric factors, engine temperature, operating conditions, and fuel quality. As the FCSV opens it allows engine vacuum, as supplied by the vacuum port on the mixer, to reach the diaphragm chamber on the regulator converter assembly. As this engine vacuum reaches the diaphragm chamber, it "pulls" on the diaphragm which in turn reduces the fuel pressure supplied to the engine. The reduction in

STRUCTURE AND FUNCTION fuel pressure has the effect of reducing the amount of fuel flow to the engine. As the DWELL of the FCSV is varied during operation, and based on input information the ECU processes, the fuel flow is adjusted accordingly. Any unapproved alteration to the vacuum lines, FCSV, and associated check valves (not described in this section) may cause the fuel control system to malfunction. Engine and catalyst damage may result and may void the manufacturer’s warranty.

Note: If during a service attempt, an ECU is not operating as described in this manual contact your local authorized Caterpillar Lift Truck dealer. Please note the truck serial number and prepare a detailed explanation of the operating characteristics prior to contacting dealer.

3. Throttle and Governor: The throttle and governor sub-system utilizes a "drive by wire" electronic throttle body. The electronic throttle body is a single "electromechanical" component. The electronic throttle body has 2 electric coils and a shaft mounted mechanical throttle valve. When voltage is applied to the coils, the shaft with the throttle valve will rotate. The throttle valve is mounted in the intake passage. As the voltage to the coils is increased, the shaft rotates opening the throttle valve, and allows increased airflow to the engine which increases the RPM. INPUT (To ECU) Throttle sensor RPM MAP

OUTPUT (From ECU) Voltage to electronic throttle body

The electronic throttle body has full authority over the throttle valve at all engine speeds and loads. The ECU will only allow the engine to operate in the manner it was programmed, and neither the operator nor service technician can alter the operating characteristic of this system without causing system failures. Idle RPM is 700. Maximum RPM is 2700. The system 49

utilizes a throttle sensor which is connected to the foot pedal either by a bracket and rod or a throttle cable, depending on the specific truck model.

Regardless of the specific throttle sensor used, the operating principals are the same. The throttle sensor includes a component called a potentiometer which relays a variable voltage to the ECU. As the potentiometer is rotated the voltage increases. The potentiometer has a voltage range from 0 volts to a maximum of 5 volts. (The minimum voltage at idle should never be less than .2 volts or at full pedal stop bolt position more than 4.865 volts.) As the operator depresses the foot pedal the throttle sensor also rotates and sends a voltage to the ECU. The ECU is programmed to interpret this voltage to a specific engine RPM. The ECU then increases voltage to the throttle body which opens the throttle valve until an engine speed is reached that is preprogrammed to correspond to the voltage output of the throttle sensor. The ECU will vary the voltage to the throttle body to open or close the throttle valve, depending on the throttle sensor position and engine load, to maintain the selected speed.

STRUCTURE AND FUNCTION 4. Throttle and Governor Operation: Upon engine cranking the ECU will automatically set the throttle valve to a predetermined position for best engine starting.

NOTE: there is no need to depress the accelerator pedal at start-up.

When the engine starts the ECU automatically opens the throttle valve to allow the engine to reach 1200 RPMs. The ECU monitors engine temperature and will set a fast idle if the engine is cold. There is a gradual return to base idle of 700 RPM as the engine temperature increases. After the short startup routine, the operator can operate the lift truck normally.

This sub-system also incorporates a RPM governing feature. The ECU will limit maximum engine RPM to 2700 regardless of the foot pedal position and load. If the engine RPM exceeds the maximum preprogrammed RPM of 3100 for an excess of 2 seconds the ECU will close the fuel lock-off valve which will shut the engine off. This is a safety feature to protect the engine and is called over speed protection.

5. Operating Specifications 4G63 / 4G64 Engines: Idle speed (Cold Engine) 700 – 1200 RPM based on engine temperature Idle speed (Warm Engine) 700 RPM Max governed speed (no load) 2700 RPM Ignition timing 10° BTDC Over speed protection Yes Condition 3100 RPM for more than 2 sec.

Result Close fuel lock-off. Engine shut down.

Over temperature protection Yes Condition Above 105 deg. C Result Check engine light flashes Condition Above 115 deg. C Result Limp home mode Max. engine speed reduced to 1200 RPM and engine is shut down if operated in excess of 45 seconds while temperature remains in excess of 115 deg. C Fuel lock-off protection

Only open when ECU detects an engine RPM.

Closed loop fuel control Condition Result

Yes A/F ratio out of spec.

Check engine light illuminated and LIMP Home mode and max speed is reduced to 1800 RPM.

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System Adjustments: 1. Diagnostic Kit Installation This system requires that the service technician have available a diagnostic device. Two diagnostic tools are available. A laptop computer with a diagnostic kit or hand held diagnostic unit are available to troubleshoot the system.

Note: This service manual will reference the Laptop diagnostic kit for troubleshooting.

The Hand Held unit will provide the same information as a laptop with the diagnostic kit. The Hand Held unit however, requires the selection of each screen individually whereas the Laptop will show all the information on one screen.

Refer to the instructions that are included with these tools for information on their use.

Diagnostic kit for Laptop Computer part #93060-06300 Hand Held Diagnostic unit part #93060-06400 This software is designed to provide diagnostic information from lift trucks equipped with the S-15G industrial engine management systems.

It is to be used with a Windows compatible PC.

SYSTEM ADJUSTMENTS 6. Select "File" in the upper left screen.

7. Select the "Comport" option and select the "Com 1" Note: After installation and before using the laptop for diagnostics use, ensure that the COM1 port is selected for use with this software.

When utilizing these diagnostic tools you will be able to access information on the following system functions. Note: Only functions frequently used to troubleshoot will be detailed fully. Refer to the instructions that are included with each of the diagnostic tools for more information. General operating specifications are included with each parameter. These values can vary from the nominal values due to variation in local atmospheric conditions, fuel quality, age of truck, hours of use, and method of operations. Values that do not fall within the ranges specified do not necessarily indicate a malfunction. Rather, these values can be used to identify operating parameters that fall outside of the average range and used to investigate or to identify a possible operational problem.

System Requirements: Pentium I or greater Windows 95, 98 or NT 16 MB memory Disk space: 86 KB

Note: These adjustments require the use of an MCFA diagnostic tool. The following instructions reflect the use of a Laptop computer with Windows based diagnostic software.

Software Installation: Insert the Diagnostic installation disk into the drive.

1. Click on START, RUN and browse to a:\Setup.exe 2. Click on OPEN. 3. Click on OK 4. Follow installation instructions displayed on screen 5. Once installation is complete, start the diagnostic software and on the S-15G screen by double clicking on the "MCFA Diag" icon on the desktop screen.

2. Adjustments: The majority of system functions and operating parameters are pre-programmed and not able to be routinely altered by service technicians.

There are several adjustments which can be made if necessary, as follows: • Idle mixture. The mixers are preset at the factory and it is not expected that routine re-adjustment will be needed in the field. Following factory adjustment, a cap is installed over the idle mixture adjustment screw to prevent tampering.

In the event a mixer is replaced or the tamper resistant cap has been removed, 51

SYSTEM ADJUSTMENTS the adjustment procedure is as follows: Connect diagnostic monitor to data port located below the rubber plug on the ECU. Start engine and allow the engine to warm-up to operating temperature.

Once engine is fully warmed-up, depress the throttle pedal to allow the engine RPM to reach an excess of 2000 RPM for at least 2 seconds.

Release throttle, fully and allow RPM to decrease to a stable idle speed. When viewing the Laptop diagnostic monitor, the parameter "DWELL" is used to adjust the idle mixture. At idle the DWELL should be adjusted to 40-50%.

This adjustment is made by turning the idle mixture screw clockwise or counter clockwise, as necessary. NOTE: During actual operation, this value can vary from the initial set point due to changes in the atmospheric conditions and fuel quality.

Therefore, if at a later date the DWELL has changed, but is still with in a 20 – 80 range and performance is acceptable, re-adjustment is not necessary.

Install tamper-resistant cap over the idle mixture screw.

Remove diagnostic equipment and reinstall the rubber plug over the data port on the ECU.

ECU adjustment: 1. Connect diagnostic monitor to the data port located below the rubber plug on the ECU. 2. Turn the key switch to "ON" but do not start the engine.

3. At the top of the S-15G diagnostic screen, select Auto Pedal function.

4. Select Manual mode.

5. Enter 195 for the High and 45 for the Low. 6. Select "OK".

The ECU has now been reset to interface correctly with the signal provided by the throttle sensor.

• Throttle system: The ECU is preset at the factory and can not be adjusted. The ECU is programmed to use the signal from the throttle sensor to appropriately adjust the engine RPM. The throttle sensor has an operating range which is greater than the range used in this lift truck application and the ECU presets are set to reflect the proper range needed. The following procedure is to be followed if these settings have been tampered with:

• Throttle Sensor Adjustment: The throttle sensor converts the movement of the foot pedal by the operator into an electronic voltage that the ECU associates with an engine RPM. In order to interface correctly with the ECU presets, the throttle sensor and foot pedal must be adjusted so that the voltage output is within the range the ECU is set to. The following procedure is to be followed to ensure correct adjustment:

1.

2.

3.

4.

5.

6.

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195

45

SYSTEM ADJUSTMENTS

1. Connect diagnostic monitor to the data port located below the rubber plug on the ECU. 2. Turn the key switch to "ON" but do not start the engine.

3. On the S-15G diagnostic screen, locate the "Pedal Angle" Note: The diagnostic monitor displays units rather than voltage. 0 units equal 0 volts. 255 units equal 5 volts 4. The value displayed should be between 28 to 45 units when the foot pedal is fully released. . ( One "unit" equals .0196 volts) If the value displayed is either below or above this value, adjustment is required. The potentiometer mounted to the throttle sensor has 2 set screws, loosen slightly to allow either clockwise or counter clockwise rotation depending on if the values are too high or too low.

Rotate the potentiometer to 35 +/- 5 units and use the data monitor screen to monitor the results. (Depending on specific truck model, throttle sensor removal from the mounting bracket may be necessary, but the electrical connection will remain connected) 5. Once rotated to the correct value, retighten the setscrews securing the potentiometer to the throttle sensor.

Reinstall the throttle sensor and the floor plate, if removal was required. This now completes the adjustment for the idle or minimum settings. The high idle or maximum setting will now be adjusted with floor plate installed.

Note: Do not apply excessive force to accelerator without floor plate installed. Damage to potentiometer may occur.

6. Fully depress the foot pedal with sufficient force to simulate actual use by an operator and apply pressure slowly.

While depressed fully note the voltage units value displayed on the diagnostic screen. The correct value should be 53

195 +/-5 units. If readjustment is necessary, loosen the locknut on the foot pedal stop bolt and adjust the height as necessary. Repeat this procedure until the correct foot pedal travel is attained to reach the desired value.

7. Once adjusted, re-tighten the locknut on the foot pedal stop bolt.

8. Remove diagnostic equipment and reinstall the rubber plug over the data port on the ECU.

SYSTEM ADJUSTMENTS 3. S-15G Screen Layout:

S-15G Screen Data Stream:

Length of Data Stream:

Must be scrolling if properly connected to ECU and key switch set to run position. If this value is not running (increasing in value) this indi cates the diagnostic cables are either not connected properly or no power is being supplied to the engine management system.

Typically 91 bytes

Analog Sensors: Pedal Angle Manifold Press.

Engine Temp.

Oxygen Volt.

Battery Volt.

0-255 Units (Typically range, 45-195 units) 36-38 kPa at no load idle to 100 kPa at full load governed speed Current value, in Deg C Displays oxy sensor voltage normal range 0.10 - .85 volt(s) Approximately 14.5v when charging

Running Parameters: Engine Speed Selected Speed Mode

Actuator Power LP Lockout Dashlight

Current value Design speed for system based on pedal position 0 Standby 1 Cranking 2 Idle 4 Normal 6 Over speed shutoff Throttle valve opening power 0-250 units 0 off, 1 on 0 off, 1 on (see "D" screen if 1 is displayed during running mode, check engine light should be displayed) 54

SYSTEM ADJUSTMENTS

3.1. Adjustments Detail: *Fuel T-Value Fuel table value *Fuel F-Value Final value after compensations *Throt. Rate Rate of change in MAP *Accel, Fast + for acceleration, - for deceleration Dwell Duty Cycle of Fuel Control Valve Solenoid, 0-100% *Oxy-Corr % of fuel adjustment due to the oxy sensor feedback *Oxy-Wait Count down timer before oxy feedback starts *On Time Comp.

Fast Acting Choke, depletes with revolutions completed * A non-adjustable preprogrammed value. Typically used only for MCFA engineering analysis.

Added Information on frequently reference parameters: Manifold Pressure: Engine manifold pressure (MAP) is an indicator of engine load. Higher loads result in numerically higher MAP value.

At idle the Manifold Pressure should be 35-45 kPa. At high idle (2700RPM) with the transmission engaged, the MAP should be 42-47 kPa. At torque converter stall (transmission engaged, brakes fully applied to prevent movement, and foot pedal fully depressed) the MAP should read about 80-100KPa for one to two seconds. If your readings are different than these, inspect the vacuum hose to be sure it is not disconnected from the ECU, the fitting on the throttle body, or damaged. There are two barbed fittings on the throttle body. The lower fitting provides the MAP signal to the ECU. The upper fitting should be connected to the distributor. If the hoses are all connected correctly and do not appear damaged, check the ignition timing. Correct timing is 10° BTDC. Engine Temp: This will vary with the temperature of the engine. If the diagnostic monitor displays either 0° or 127°C it may indicate the temperature sensor has been physically damaged, a electrical short circuit occurred, or the sensor has been disconnected.

Battery Volts: This is simply an indication of the Battery Voltage and will vary with the bat55

tery state of charge and alternator output.

When the engine is not running it should be close to 12 Volts. When the engine is running and there is an output from the Alternator you should see approximately 13-15 Volts depending on the battery's condition.

Actuator Power: This is the voltage signal the ECU sends to the Throttle Body Governor to energize the coils that controls the valve. At idle, it will read approximately 20-30 units, increasing with higher RPMs. At maximum load the output will be about 170-220 Units (Converter Stall Condition). NOTE: These values can vary significantly, but can be used to compare from one running condition to another and this trend of voltage change versus engine RPM and load can help during troubleshooting.

Dwell: This value is the amount of time the Fuel Control Solenoid Valve (FCSV) is activated and open to vacuum, by the ECU. The FCSV operates at specific "DWELL" based on fuel requirements. A 50% dwell means the valve is open 50% of the time and closed 50% of the time. A DWELL of 100% indicates that the valve is open 100% of the time and the fuel control system is at full "lean". A DWELL of 0% indicates that the valve is closed 100% of the time and the fuel control system is full "rich".

SYSTEM ADJUSTMENTS 3.2 Diagnostic Screen Layout: Diagnostic "D" Codes Screen

Data Stream: Length of Data Stream: Com Port: Program Version: Map Version: Check Engine Codes:

Must be scrolling for proper connection to ECU Typically 91 bytes Shows Com Port selected from pull-down menu Indicates EPROM installed in ECU Indicates ECU calibration NONE - No check engine codes BAT Battery Voltage Error CHRG - Charging System Error ETMP Engine Block Temperature Sensor Error HTMP - High Engine Block Temperature KILL Emergency Engine Shutdown Activated MAP Manifold Absolute Pressure signal Error OXY Oxygen Sensor Error/Fuel System Error THRPedal Sensor out of Range/Open Circuit TRIG TACH Signal Error

56

TROUBLESHOOTING

S-15G Fuel System Troubleshooting: Introduction: The majority of possible malfunctions can cause differing symptoms depending on the specific cause and frequency of occurrence. For example, an intermittent electrical short could sometimes prevent an engine from starting and at other times cause intermittent stalling or rough operation.

1. Trouble Shooting Detail: 1.1 Problem: Engine "turns over" when starter motor is engaged, but will not start.

Analysis: First, Check LPG tank and supply hoses and filters. Most often there are 2 reasons an engine will not start if there is fuel available. Either the malfunction is in the ignition system or the fuel supply system. Note: This manual is intended as a supplement to detail the engine management system. The ignition system and test methods are covered in more detail in the chassis service manual. Once it is established the ignition system is working properly, the fuel supply system will need to be evaluated. It needs to be determined if LPG fuel is being supplied to the engine. The following steps should be followed: 1) Connect the diagnostic monitor to the ECU and go to the "S" screen.

2) Turn the key to the "run" position, but do not engage the starter motor. The data stream should begin counting. If there is no Data Stream, check the data monitor cables for proper installation. If there is still no data stream, the engine management system may not be getting power. Check the electrical connections that supply power and ground to the engine management wiring harness. (See wiring harness schematic). If all the connections are intact, remove the connector from the ECU and use a Fluke 87, OTC 600, or equivalent meter to test for a 12V-power supply on pin #4 and for ground on pin 8.

57

3) If 12 volt power to pin 4 and/or ground connection to pin 8 is not indicated, use general electrical troubleshooting procedures to track down the cause.

(Reference the engine management wiring harness in the schematic section of this manual and the chassis wiring harness schematic in the chassis service manual.)

4) If the ground and power supply are working correctly, turn the key off and reconnect the ECU connector. View the data monitor while engaging the starter motor by moving the key to the start position for approximately 10 seconds.

5) While the starter motor is engaged and viewing the data monitor, check to see if a RPM is being displayed in Engine Speed indicator. If no RPM is being registered, this may signify a wiring problem between the distributor and the ECU on pin #1.

Investigate and repair. If no problem is found an ECU failure may have occurred.

Replace ECU. 6) If the RPM is being registered, check the lock off valve for proper function. The lock off will open only when the ECU detects a RPM during starting which is a method of reducing the chance of a LPG leak.

Disconnect the connector from the wiring harness to the lock off. Connect the electrical meter to the connector on the wiring harness and check for 12-volt power to the lock off when the starter motor is engaged and while the Data monitor is registering RPM. If no power is being supplied to the lock off during starting, inspect and repair the wiring harness. If no wiring problem is detected, an ECU failure may have occurred.Replace ECU 7) If power is being supplied to the lock off, but it is not opening properly, test LP lock off Solenoid coil for open circuit. Repair as needed.

TROUBLESHOOTING 1.2. Problem: Engine starts, but stalls immediately Analysis: If an engine starts, but runs poorly, the potential causes are listed below: Note: * please refer to the Chassis service manual for further explanation.

• LPG regulator converter malfunction. If defective replace entire regulator assembly.

No kit is available.

• Mixer malfunctions. Check and clean. If defective replace entire mixer assembly.

No kit is available.

• Leaks in LPG supply lines.

• Operating temperatures below -20° F resulting in cold LPG tanks which can result in low tank pressures.

• * Ignition system malfunctions.

• Fuel supply restricted or cut off.

• * Engine in questionable condition.

1.3. Problem: Rough unstable idle. Poor acceleration. High engine idle.

Analysis: A rough or unstable idle can have many potential causes. The first step at diagnosis is to perform the following inspections: Note: * please refer to the Chassis service manual for further explanation.

• Inspect the vacuum lines: (see vacuum hose diagram) • mixer to the FCSV • throttle body to the distributor • throttle body to the ECU. • * Check air filter and clean or replace.

• Check LPG filter.

• * Vacuum leaks in the intake system.

• Engine block temperature sensor. The sensor should be registering a temp of approximately 65 ° to 90° C depending on ambient conditions, length of time running and load used. Generally speaking, the temperature displayed should increase appropriately following initial startup and this indicates proper operation.

• * Ignition system and timing check. Inspect for proper operation.

• Inspect and clean the check valve in the balance line. (See vacuum hose diagram).

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•

This check valve is intended to move freely in the housing. If the ball seems to be stuck or not moving freely, clean with an oil and residue free automotive type cleaner.

For a high engine idle see all comments above. Also, check to ensure the min and max values in the ECU and throttle sensor are adjusted properly. On cushion type models check throttle cable as a minimum of only 1/8 inch slack.

TROUBLESHOOTING 1.4. Problem: The check engine light comes on intermittently while the engine is allowed to idle for extended periods of time.

Analysis: Some trucks in the field can occasionally have this happen. In the event this problem occurs and also is accompanied by a "buzzing" noise coming from the mixer.

This "buzzing" can be corrected by adjusting the "minimum" limit set screw on the throttle body.

1) Remove the throttle body from the intake manifold.

2) Locate the correct setscrew. (see diagram for location of setscrew) 3) Turn the screw counter clockwise 1 turn.

4) Reinstall the throttle body and check for operation.

5) If not corrected repeat the same procedure as above and rotate the setscrew an additional HALF turn counterclockwise.

6) If problem is not corrected contact your local Authorized Caterpillar dealer for further assistance.

59

TROUBLESHOOTING

Rough/Unstable Idle

Engine does not start / Fuel

2. Trouble shooting Tree Detail No LP-gas in tank.

Refill LP-gas tank.

Improper operating procedure.

Check outlet valve on LP-gas tank is open.

Do not press accelerator pedal with start up.

Is LP-gas is supplied to convertor?

Check yellow/blue wire (Pin #4) to battery positive with key switch on.

No power, repair open wire or replace wire harness.

Does Fuel Lock Off have power?

Check for 12volt power with engine cranking over.

No power, Repair open wire or replace wire harness.

Wires OK, Replace ECU

Check for Spark.

Check Battery Check Spark Plug Gap. Inspect Coil Wire Harness.

Distributor Pickup.

Check Mechanical Conditions.

Check Engine Condition (Mechanical).

Check Fuel System (Mechanical).

Check Vacuum Hoses.

See Vacuum hose diagram for routing.

Check Engine Block Temp Sensor.

If disconnected the reading will be 127 degree C on the diagnostic screen.

Check Oxygen Sensor.

Check connection.

Check Ignition System.

Check spark plug connections and condition.

Test primary and secondary Ignition systems.

Check Fuel level

Check LP-gas tank level.

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Poor Acceleration

TROUBLESHOOTING

Is engine getting Air?

Check Air Filter

Check Map Sensor Vacuum hose.

Is hose disconnected, pinched or plugged?

Map Sensor should read 35-45 kpa at idle.

Map Sensor does not change Replace ECU with raise of rpm,

Connect Diagnostics & Check For Codes

Pedal Sensor Adjustment Dwell

O2 Voltage

High Engine Idle

Map

Clean or Replace.

Select RPMS (2700) Pedal units (195) Idle?

Full RPM? Stall?

Idle?

Full RPM? Stall?

Idle?

Full RPM? Stall?

Check Valve Test (Balance Line) Ball.

Ball must move freely and be free of oil.

Clean or Replace.

Ignition Timing.

Actual Misfire

Check Pedal Position Adjustment.

See Pedal Position Adjustment section.

Check Ignition Timing.

Engine Timing 10˚ BTDC.

Check for Intake manifold or Throttle Body gasket leaks.

Spray suspected area with WD40, the engine will suck into the combustion chamber and the engine rpm raise.

Retorque bolts.

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TROUBLESHOOTING 3. Check Engine Light Blink Faults Blink Codes: a series of regular flashes of the Check Engine Light. These maybe diagnostic codes or warning codes.

Warning codes occur while the engine is running.

Diagnostic codes are displayed when the engine RPM is "0" and the key is in the "run" position.

When the key switch is turned on, the Check Engine Light is illuminated to show that the lamp is operational. If the engine is not started, the light will turn off after 20 seconds. If error codes are detected (RPM=0), the light will begin to blink codes sequentially after an additional 15 seconds.

Condition

Lamp Status

Indication

RPM=0 RPM=0 RPM>0 RPM>0 RPM>0 RPM>0

Lamp off after 30 seconds After 45 seconds, Lamp flashes Lamp off Lamp blinks slowly Lamp blinks quickly Lamp on steady

No error codes Shows error codes Normal operation Charging system problem Overheat / Over speed Other error detected

4. System Fault Codes After 45 seconds in standby mode, the Check Engine Light will blink to display any known faults.

The light will blink in one second intervals to indicate the following errors. In the case of multiple codes, there will be a five second pause between code sequence.

Number of Flashes 3 4 6 8 9

Fault Indication Fuel System error Pedal Sensor open Engine Temperature Sensor Battery Voltage TACH. (RPM input)

Note: These codes will also be displayed on the handheld monitor or laptop display if an error is apparent during normal operation.

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TROUBLESHOOTING 5. Effects of Fault Conditions Note: The ECU does not store fault codes, at restart the system will cycle through self test and energize the Check Engine Light if a fault condition remains.

Code acronym displayed on diagnostic screen of handset or PC. Voltage Error: BAT (8 flashes)

ECU Function: The ECU checks the charging circuit for alternator output voltage. If voltage is below 12 volts the Check Engine Light will illuminate. If charging voltage returns to specification the light will turn off after the next successful test.

Effects on Operation: No immediate change to operation, governor performance may suffer.

Voltage Error: CHRG (0 flashes)

ECU Function: The ECU checks the charging circuit for alternator output voltage. If voltage is above 15.5 volts the Check Engine Light will illuminate. If charging voltage returns to specification the light will turn off after the next successful test.

Effects on Operation: No immediate change to operation, governor performance may suffer.

Engine Temp Sensor: ETEMP (6 flashes)

ECU Function: ECU will display 127° C. on diagnostic display. The Check engine Light will flash.

Effects on Operation: No cold engine operation or fuel compensation. Loss of cold engine operation.

Possible Cause: Faulty sensor or open/shorted wiring problem.

Temp Error: HTEMP (6 flashes)

ECU function: Over 105° C. Check Engine Light flashes.

Over 115° C. engine enters limp home mode, engine RPM reduced to 1200 RPM. Engine shut down occurs after 45 seconds.

After engine restart, system will not check for over temperature for another 45 seconds.

Effects on Operation: Engine RPM is reduced to 1200 RPM, engine shut down occurs 45 seconds later.

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TROUBLESHOOTING Oxygen Sensor: OXY (3 flashes)

ECU Function: Oxygen sensor voltage 0.1 volts to 0.85 volts out of range, Check Engine Light is illuminated.

Effects on Operation: Engine enters Limp Home Mode, Check Engine Light is illuminated.

Maximum engine speed is reduced to 1800 RPM.

Fly Wheel Sensor: TRIG (9 flashes)

ECU Function: ECU does not see engine TACH signal. Open wire to ECU. Effect on Operation: Fuel lock of will not function. Engine will not operate without TACH. signal.

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65

-

-

-

A B C

D E F G

H I

LP VAPORIZER/ REGULATOR

LIQUID PROPANE IN

B C

G

FILTERED INTAKE AIR

F

FUEL CONTROL SOLENOID VALVE HIGH PRESSURE LP REGULATED PROPANE GAS ATMOSPHERIC PRESSURE COMPENSATION CONTROL SIGNAL VACUUM CHAMBER DIAPHRAGM RESTRICTOR CHECK VALVE FUEL CONTROL SOLENOID VALVE AIR/GAS MIXER DIAPHRAGM/METERING VALVE

A

D

E

GASEOUS PROPANE OUT

I

TO THROTTLE BODY

AIR / GAS MIXER

H

SCHEMATICS

1. CARB 1 Tier 1 LP Fuel Vacuum System Diagram

ECU Connector as seen from Harness side

66 GREY

WHITE

BLACK/WHITE

GREEN

ORANGE

BROWN

RED

WHITE

FCSV

GROUND

ACCELERATOR SENSOR

OXYGEN SENSOR

DISPLAY CONNECTOR

PURPLE

BLACK

BLACK

KEY SWITCH

BLUE/YELLOW

CHECK ENGINE LIGHT

RED RED RED

YELLOW/GREEN

GROUND

BLACK

CARBURETOR THROTTLE BODY

15 AMP FUSE IN CONSOLE

BLACK/RED

BLACK

RED

BLACK

FUEL LOCK OFF

YELLOW/BLUE

BLUE/BLACK BLACK RED

GREEN/BLACK

S15G SYSTEM

TO BATTERY +

THERMAL RESISTOR AT ENGINE BLOCK

BLACK

BLUE

COIL

SCHEMATICS 2. CARB 1 Tier 1 Wiring Schematic

SCHEMATICS 3. CARB 1 TIER 1 ECU Pin Location Pin #

Color

Function

1

Red(R)

TACH Signal (To coil NEG)

2

Yellow/Green (Y/G)

Console System Fault Light (Check Engine Light NEG)

3

Green (G)

Throttle Pedal Sensor (0.3-4.7 volt input to ECU)

4

Yellow /Blue (Y/L)

Battery Power (Key switched-Fused)

5

White (W)

Oxygen Sensor (Signal to ECU)

6

Green/Black (G/B)

(NEG connection to ECU) LPG Lock Off

7

White (G)

Fuel Control Solenoid Valve (NEG connection to ECU)

8

Black (B)

Battery NEG to truck frame

9

Orange (OR)

Pedal Angle Sensor (5 volt source from ECU)

10

Black/White (B/W)

Pedal Sensor Filtered Ground (NEG connection to ECU)

11

Brown (Br)

Engine Temperature Sensor (Signal to ECU)

12

Blue/Black (L/B)

Throttle Body Governor Signal (Variable voltage output from ECU)

67

ECU Connector as seen from Harness side

GREEN/BLACK

COIL

BLACK

CARBURETOR THROTTLE BODY

BLACK

RED

RED RED RED

BLUE/BLACK BLACK RED BLACK BLACK/RED

BLUE

GROUND BLUE/YELLOW

66

15 AMP FUSE IN CONSOLE

YELLOW/BLUE YELLOW/GREEN FCSV

PURPLE

KEY SWITCH

BLACK

TO BATTERY +

CHECK ENGINE LIGHT

DISPLAY CONNECTOR

WHITE

RED

WHITE

GREY

BROWN

OXYGEN SENSOR

GROUND

ORANGE

BLACK

GREEN

BLACK/WHITE

THERMAL RESISTOR AT ENGINE BLOCK

ACCELERATOR SENSOR BLACK

SCHEMATICS

FUEL LOCK OFF

2. CARB 1 Tier 1 Wiring Schematic

S15G SYSTEM

SCHEMATICS 3. CARB 1 TIER 1 ECU Pin Location Pin #

Color

Function

1

Red(R)

TACH Signal (To coil NEG)

2

Yellow/Green (Y/G)

Console System Fault Light (Check Engine Light NEG)

3

Green (G)

Throttle Pedal Sensor (0.3-4.7 volt input to ECU)

4

Yellow /Blue (Y/L)

Battery Power (Key switched-Fused)

5

White (W)

Oxygen Sensor (Signal to ECU)

6

Green/Black (G/B)

(NEG connection to ECU) LPG Lock Off

7

White (G)

Fuel Control Solenoid Valve (NEG connection to ECU)

8

Black (B)

Battery NEG to truck frame

9

Orange (OR)

Pedal Angle Sensor (5 volt source from ECU)

10

Black/White (B/W)

Pedal Sensor Filtered Ground (NEG connection to ECU)

11

Brown (Br)

Engine Temperature Sensor (Signal to ECU)

12

Blue/Black (L/B)

Throttle Body Governor Signal (Variable voltage output from ECU)

67

INSPECTION AND ADJUSTMENT

Converter (Vaporizer)

LP-gas carburetor Low-pressure hoses (gas hoses) Hot-water hoses Engine

Every 4800 service hours or 2 years

LP-gas filter

Every 2400 service hours or 1 year

High-pressure hoses

Every 1200 service hours or 6 months

LP-gas tank and bracket

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Every 10 service hours or daily (pre-start)

item

Every 200 service hours or monthly

1. Periodic inspection schedule

service

Check bracket for installation.

Check bands for tightness.

Check valves and gauge for leaks.

Check hoses and fittings for damage.

Replace hoses.

Check for installation.

Check fuel lines for leaks.

Replace kit parts.

Replace Assembly (S-15G System) Remove tar.

Check connectors for tightness.

Check fuel lines for leaks.

Replace kit parts.

Check for installation.

Check fuel lines for leaks.

Replace kit parts.

Check for installation.

Check bands for tightness.

Check for damage.

Check bands for tightness.

Idling and acceleration CO measurement Check Faults and Codes

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