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1. General Information Troubles Diagnosis A. Engine hard to start or can not be started Check and adjustment
Fault condition
Loosen carburetor drain bolt to check if there is gasoline inside the carburetor Fuel supplied tom carburetor sufficient
No fuel is supplied to carburetor
Remove spark plug, install it into spark plug cap, and perform a spark test against engine ground.
Check if sparks
Weak sparks, no spark at all
Perform cylinder compression pressure test.
Cylinder compression pressure normal
Low compression pressure or no pressure
Probable causes
1. No fuel in fuel tank 2. Check if the pipes, fuel tank to carburetor and intake vacuum, are clogged. 3. Float valve clogged 4. Lines in fuel tank evaporation system clogged 5. Malfunction of fuel pump 6. Loosen or damaged fuel pump vacuum hose 7. Fuel filter clogged
1. 2. 3. 4. 5. 6. 7.
Malfunction of spark plug Spark plug foul Malfunction of CDI set Malfunction of AC generator Ignition coil is in open or short circuit Ignition coil leads open or short circuit Malfunction of main switch
1. 2. 3. 4. 5.
Piston ring seized Malfunction of cylinder valves Worn cylinder and piston ring Cylinder gasket leak Sand hole in compression parts
Re-start by following the starting procedures
No ignition
There are some signs of ignition, nut engine can not be started
1. Malfunction of throttle valve operation 2. Air sucked into intake manifold 3. Incorrect ignition timing
Remove the spark plug again and check it.
Dry spark plug
Wet spark plug
1. 2. 3.
Fuel level in carburetor too high Malfunction of throttle valve operation Throttle valve opening too wide
Blowing clogged
1. Malfunction of automatic by- starter
Remove carburetor after 30 minutes and connect a hose onto fuel rich circuit. Then blow the hose with air
Blowing in normal
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