Engine Instrumentation Problems and Solutions tronic shop gauges necessary to verify exactly what’s going on with your engine. Once proper operation has been verified in this manner, record the normal readings of your gauges. Remember, while underway you’re looking for readings outside these pre-established norms. If you follow the steps outlined in this chapter, you’ll have the confidence and ability to tackle and repair most instrument failures that crop up on your boat. Remember that, as with all the other sections of this book, you should never attempt to go too far with your diagnosis and repair without the aid of your workshop manual. Also remember that the basic electrical troubleshooting and repair procedures already discussed will carry you through any diagnosis of instrument problems.
The Future
Fig. 10-9. An oil-pressure sending unit on a GM V8 engine. On this engine it’s located next to the ignition distributor.
Figures 10-10a and 10-10b show how far we have come since the first edition of this book. New boats today will likely be equipped with a networked system for distributing engine data, among other things. The Mercury Marine SmartCraft display in figure 10-10a is an integrated part of that system, and effectively replaces the traditional gauges discussed in this chapter. The data come from an engine-mounted computer like the one shown in figure 10-10b. All wiring is done through proprietary harnesses with multiple-pin plug assemblies as in figure 10-10b. Troubleshooting instrumentation problems on these systems is a bit more
complicated than some of the procedures described for conventional instruments. But with an ohmmeter, you can check continuity of the pin connections from one end of the harness to the other and at least determine if there is a problem with the harness or a plug assembly. Beyond that there is not much you can do without specialized equipment that goes beyond the scope of this book. One resource for those that want to learn more about these systems is my latest book, Advanced Marine Electrics and Electronics Troubleshooting.
Fig. 10-10a. SmartCraft display.
Fig. 10-10b. Engine-mounted computer.
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