Cavalier/Z24 L4-144 2.4L DOHC VIN T SFI (1996)
Fuel Pump Signal: 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. As a
backup system to the fuel pump relay, the fuel pump also can be energized by the fuel pump and the engine oil pressure indicator switch. The fuel
pump and the engine oil pressure indicator switch is a normally open switch which closes when the oil pressure reaches about 28 kPa (4 psi).
Whenever the fuel pump relay fails, the fuel pump and engine oil pressure indicator switch 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.
