Service manual

90-898303

3-6

An overheat condition will occur if engine temperature exceeds 200° F (93°

C). A constant warning horn will sound as long as the overheat condition

exists. If the overheat condition should occur at wide-open-throttle, the engine

RPM will be reduced to 3000. The engine will return to normal operating

condition when the temperature drops below 200° F (93° C).

The temperature sensor can be tested using a digital volt/ohm meter.

NOTE: If sensor does not make clean contact with cylinder head, a rich

condition may exist.

THROTTLE POSITION SENSOR (TPS)

The TPS transmits information to the ECM during low speed and mid range

operation, related to throttle angle under various load conditions. TPS

adjustment is a critical step in engine set up.

Other Components Associated With the ECM.

IMPORTANT: When disassembling EFI System DISCONNECT BATTERY

CABLES.

FUEL INJECTORS

A four wire harness connects the fuel injectors to the ECM. The RED wire is at

12 volts and connects to all injectors. The BLUE, YELLOW and WHITE wires

each go to a pair of injectors and are normally at 12 volts for a zero

differential. To fire the injectors this voltage is brought down to near ground

creating a potential across the injectors.

ELECTRIC FUEL PUMP

The EFI ECM contains a fuel pump driver circuit that provides power to the

electric fuel pump. The amount of time the fuel pump operates varies with the

RPM of the engine. Above approximately 3000 RPM, the fuel pump is

operating continuously (or at 100% of its duty cycle).

WATER SENSING SYSTEM FUNCTION

The system consists of a water separating fuel filter (starboard side

powerhead) and a sensing probe (bottom of filter).

1) The filter separates the accumulated water from the fuel.

2) A voltage is always present at sensing probe. When water reaches top of

probe it completes the circuit to ground.

3) The completed circuit activates the warning.

NOTE: The water detection light will stay on and the warning horn will “BEEP”

4 times and remain off for 2 minutes. This cycle will continue until the water is

removed. This warning is the same as for the “Low Oil” warning.

The system can be tested by disconnecting the TAN wire from sensor probe

and holding to a good engine ground connection for 30 seconds.

Notes

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