Fuel Pump Circuit

When the key is first turned ON, the PCM energizes the fuel pump relay for two seconds to build up the fuel pressure quickly. If the engine is not started within two seconds, the PCM shuts the fuel pump OFF and waits until the engine is cranked. When the engine is cranked and the RPM signal has been detected by the PCM, the PCM supplies 12 volts to the fuel pump relay to energize the electric in-tank fuel pump.

As a backup system to the fuel pump relay, the fuel pump can also be energized by the fuel pump and engine oil pressure indicator switch. The normally open switch closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump and engine oil pressure indicator switch will close and run the fuel pump.

An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold. An inoperative fuel pump would cause a no start condition. A fuel pump which does not provide enough pressure can result in poor performance.