Fuel Pump: Description and Operation

Fuel Tank And Fuel Pump Module View.:

ELECTRIC FUEL PUMP
The electric fuel pump used on Saturn vehicles is in the fuel tank and is serviceable.

If the fuel system is suspected of delivering an improper amount of fuel, it should be inspected and tested in the vehicle.

FUEL PUMP CONTROL
The PCM controls the in-tank electric fuel pump by energizing or de-energizing the fuel pump relay. When the ignition key is first turned to the Run position, the PCM will energize the fuel pump relay, by supplying power, for approximately two seconds to pressurize the fuel system. If the vehicle is started and engine references pulses are received from the ignition module, the fuel pump relay will be left energized. If the engine is not started within approximately two seconds, the relay will be de-energized. The relay will be energized as soon as engine reference pulses are received from the ignition module. When the ignition key is turned to the Off position the fuel pump relay will be de-energized. The fuel pump relay will also be de-energized within approximately two seconds, if engine reference pulses are not received from the ignition module. This is a safety feature, in case of an accident the fuel to the engine compartment is shut-off.


FUEL PUMP RELAY
To control fuel pump operation, a fuel pump relay is used. When the ignition switch is turned to the RUN position, the fuel pump relay activates the electric fuel pump for 1.5 to 2.0 seconds to prime the injector. If the PCM does not receive reference pulses from the crank position sensor and ignition module after this time, the PCM signals the relay to turn off the fuel pump. The relay will once again activate the fuel pump when the PCM receives reference pulses.