Fuel Pump Relay: Description and Operation

When the ignition key is first turned to the "ON" position, the Powertrain Control Module (PCM) will energize the fuel pump relay as long as the engine is cranking or running, and the PCM is receiving distributor reference pulses. If there are no reference pulses, the PCM will shut "OFF" the fuel pump relay within two seconds.

An inoperative fuel pump relay can result in extended crank times, particularily if the engine is cold. The oil pressure switch will turn "ON" the fuel pump, as soon as oil pressure reaches about 28kPa (4psi).