Questions and Answers

OPS Kills Fuel Pump?? Q. Hey Vincent, how you doing? At first I thought the oil pressure switch that is in the fuel pump circuit on a chevy EFI was a safety shutoff. Now I'm told that isn't true, it is just a redundant power supply for the pump. I have read articles that said that switch could kill the voltage to the pump, but the article wasn't model or engine specific.

All the diagrams I have looked at concerning the fuel pump circuits all show that switch to be wired in parallel. It can not kill the pump relay being wired like that. I even unplugged that switch on my old car with MPFI, it started and ran just fine. I have had folks say that diesel or marine applications may do this. I don't know?

Do you know of any Chevy, EFI, gasoline-non-marine, TBI, TPI, SFI where that switch will kill the fuel pump? If you do, can you give the year - model - engine info? I do realize if the pump relay totally quits, then the oil pressure switch could kill the engine.

Anyway thanks,
Janey

A. From what I remember, that switch is there in case the relay goes bad. This way the engine will have an extended crank until it goes above 7 psi oil pressure to close that switch and it will turn on the fuel pump.