1991 s10 pickup fuel pump shutting off intermediate some times not at all.
I have replaced the fuel pump, the screen, the fuel filter, rebuilt the fuel
pressure switch, and changed the two relays under the hood. When turning
the key forward to start the engine, the pump kicks on and shuts off just like it
should. Turn the engine off and that is when I have the problem. Will actually
kick off for a split second, then kick back on.
So it's like it is getting power after you turn the key off?
yes it should run for a few seconds when you turn it off but it just keeps running
Chances are it would be in the ignition switch. Thats what kills all the power.
The pump still has to pressurize after the key is turned off. Is there a sensor that senses when the system is pressurized and cuts power to the pump?
I found a fuel pump cut off switch that they say is on your truck. I wouldn't know where it is, but if you ask at the parts store, they may be able to tell you. Also found that there is a fuel pump relay that would make sense to try.
This is an update, the problem has been solved. It was the oil pressure switch. It was showing oil pressure after the motor was shut off so it was sending the message to the computer that it had oil pressure meaning that the motor was running so the fuel pump would not shut off. This is a new one on me, but thanks everyone for all of your help.
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