Seville V8-273 4.5L (1989)
Oil Pressure Switch (For Fuel Pump): Description and Operation
As a backup system to the fuel pump relay, the fuel pump can be energized by the oil pressure switch. The oil pressure switch has two internal circuits.
One circuit operates the oil pressure indicator lamp, and the other is a normally open switch that closes when oil pressure reaches approximately 4 psi. If
the fuel pump relay fails, the oil pressure switch contacts will close and run the fuel pump.
An inoperative fuel pump relay can result in extended cranking times, especially when the engine is cold. If the fuel pump relay is inoperative a code
will be set. The oil pressure switch acts as a backup to the relay to energize the fuel pump as soon as oil pressure reaches approximately 4 psi. An
inoperative fuel pump would cause a no start condition. A fuel pump which does not provide enough fuel pressure may result in poor engine
performance.
