Fuel Pump Electrical Circuit

When the ignition switch is turned to the ON position, the VCM energizes the fuel pump relay for 2 seconds allowing the fuel pump to pressurize the fuel system. If the VCM does not receive any ignition reference pulses (engine cranking or running) within 2 seconds, the VCM de-energizes the fuel pump relay. This causes the fuel pump to stop.

As a backup system to the fuel pump relay, the fuel pump can be energized by the fuel pump and engine oil pressure indicator switch. The switch has the 2 following internal circuits:

1. The oil pressure indicator or gage in the instrument cluster.
2. A normally open switch which closes when the oil pressure reaches about 28 kPa (4 psi).

If the fuel pump relay fails, the fuel pump and engine oil pressure indicator switch runs the fuel pump. An inoperative fuel pump relay can result in long cranking times. The fuel pump and engine oil pressure indicator switch energizes the fuel pump as soon as the oil pressure reaches about 28 kPa (4 psi).