Cadillac Repair: Cadillac Starting Problem, oil pressure switch, fuel pump relay

Question
I have a 1990 Deville 4.5L v-8 that runs great 99% of the time. Once in a while, it will not start. Might be a fuel problem so I changed the fuel pump. Still won't start(intermittent).I hear there is a fuel pump relay that runs the pump for a few seconds and then the oil pressure switch takes over and provides voltage to the pump. Where is the fuel pump relay? How hard to change?

Answer
Using 2 people, Perform the following:

Fuel pump test:

1. Get yourself a helper.

2. remove the gas cap.

3. have one person listen in the gas tank at the gas cap opening.

4. have the other person turn the ignition switch to the ON position ONLY so as the dash lights come on. Do NOT attempt to start the engine.

5. As soon as the ignition key is turned to the ON position, The person at the gas tank should hear the fuel pump run for TWO SECONDS and then it should STOP.

6. Does it ?.

7. If the pump DOES run for the 2 seconds and then STOP, The fuel pump relay is OK.


let me know.


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