Engine Instrumentation Problems and Solutions inducing the engine to seize. Once the engine has had a chance to catch its breath and stabilize somewhat, shut it off and let it cool down enough so you can check the level of cooling water if you have a freshwater-cooled engine. Next check for a broken fan belt on the water pump. If the belt is in order, the most likely cause for overheating is a blocked water intake to the engine’s cooling system. Follow the steps outlined in your workshop manual to determine if adequate cooling water is entering the system. Often the problem is a piece of debris that’s drawn to the intake port by the suction of the water pump. In many cases, stopping the boat and backing down for 10 or 20 feet will dislodge the foreign object, and all will be well. In any event, you should spend some time reviewing your engine workshop manual, getting familiar with the cooling system and troubleshooting procedures before problems develop. Carry spare water-pump impellers and fan belts at all times.
Low Voltage Reading If your volt gauge suddenly shows a lower-thannormal or a higher-than-normal voltage reading, you can easily verify the accuracy of the gauge by doing an open-circuit voltage test at your battery. Use your multimeter and take the reading with the engine running as outlined in chapter 5.
Low or High RPM Irregular engine rpm usually shows up as an erratic reading or no reading at all on the tachometer. If the engine is running normally in spite of the erratic reading, get the boat back to shore and follow the electrical troubleshooting steps outlined in the next section of this chapter.
Trim-Gauge Problems Of all the instruments on a boat with an inboard/ outboard engine, the trim gauge is the one with the highest failure rate. This is because the sending units on these boats are often located underwater on the side of the engine drive unit. Here they are exposed to the worst environment any electrical equipment can experience.
Faulty trim-gauge readings always indicate an electrical malfunction and have nothing to do with the function of the drive itself. To be safe, take a look over the transom just to be sure the drive is down before starting the engine. On inboard engines, hydraulic trim tabs operated by an electric servomotor control trim. They have a comparatively low failure rate, because all the electrical components are located inside the hull and are not exposed to seawater.
Fuel Gauge Problems Common sense should assist you with any erratic reading on your fuel gauges. As soon as you buy a new boat, you should establish an approximate fuelconsumption rate. Calculate the gallons of fuel used by your engine per hour of running time at different rpms. Based on that usage and the capacity of your fuel tank, you should be able to estimate the amount of fuel in your tank and use that estimate to judge the accuracy of your fuel gauge. For example, if you burn 10 gallons per hour at 3,000 rpm and have a 50gallon fuel tank, you can safely operate your boat for four hours and still have an emergency reserve, no matter what your fuel gauge tries to tell you. Problems with fuel gauges, like problems with trim gauges, are almost always the fault of the tank sending unit. The test procedure for this will be found later in this chapter.
General Instrument Troubleshooting The pros say that whenever an instrument problem crops up, you should always verify that a problem does in fact exist by swapping the engine gauge with a quality shop gauge, which is often a mechanical gauge. This is good advice, but unless you have a personal friend who’s a mechanic (which is a great idea), you probably won’t have ready access to a set of quality shop gauges. The tips that follow will help you around this deficit and to successfully solve most instrument problems. Remember, if you still have doubts about your abilities to attack your instrument problems after reading the steps outlined here, your best bet is to call in a pro who has the equipment to do the job properly. 149
