X-No-Archive: yes
I can't speak about the other cars but I know that if I turn on the key and don't start the truck with in 30 sec I have to recycle the key. If I don't it doesn't start. So for the 91 suburban at least the oil pressure switch does control the fuel pump. Actually the computer controls the fuel pump but it does use input from the sender.
mark
the computer doesn't control the fuel pump. the fuel pump relay does. the OP switch only comes into play if the FP relay has failed.
-Bret
the ECM turns on the fuel pump relay (and thus the pump) at key-on to prime the system, then shuts it off until it sees ignition pulses
when it sees ignition pulses, the relay comes on again
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