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4.3GL, 5.0GL, and 5.7GL Models
Operation
The electric fuel pump utilizes a 12 volt DC motor that runs continuously at 4000 RPM whenever the engine is
cranked or running. The electric motor drives a metal gear pump that uses the fuel as coolant. The pump supplies
fuel at variable PSI as determined by engine load and fuel consumption. Excess fuel circulates within the pump
past an internal pressure regulator. When the regulator is in operation, fuel stops entering the pump. This design
eliminates the need for a return line to the fuel tank.
The pump has excellent dry prime characteristics, and can run without fuel for up to 30-40 seconds, although
running without fuel is not recommended. The carburetor float chamber will run out of fuel before damage could
occur. The fuel pump has an in-line Radio Frequency Interference (R.F.I.) suppressor built into the motor’s plastic
connector. A separate circuit breaker provides circuit overload protection.
When the key switch is turned to the “START” position, voltage is supplied to the fuel pump relay from the start
(“S”) terminal of the assist solenoid. The relay is activated and battery voltage is applied to the pump motor and
then to engine ground.
The alternator supplies voltage to the relay from the “light” terminal after the engine starts and the key switch is
returned to the “RUN” position. The pump relay also receives voltage direct from the battery via the assist solenoid,
and this circuit is protected by a 7.5 amp fuse.
A diode in the yellow/red lead prevents voltage feedback from the alternator to the assist solenoid. This keeps the
starter motor from being energized after the engine starts. A diode in the alternator green lead prevents damage
to the alternator during cranking.
