Fuel Pump: Description and Operation

Fuel Pump Electrical Circuit

When the key is first turned ON, without the engine running, the PCM energizes the fuel pump relay for a calibrated time (approximately 2 seconds). This builds up fuel pressure quickly. Whenever the engine is not started within two seconds, the PCM shuts OFF the fuel pump and waits until ignition reference pulses are present. As soon as the engine is cranked, the PCM energizes the relay which powers the fuel pump. An inoperative fuel pump relay can result in long cranking times. An inoperative fuel pump would cause a no start condition. A fuel pump which does not provide enough pressure can result in poor performance.