Butchart

I have a problem with my 1988 F-150 302 V8 EFI. When I shut the engine off, the fuel pumps keep going. They have two, the low pressure one in the fuel tank and the high pressure one attached to the frame rail. It started couple weeks ago, they would run for up to a minute, but now they don't shut off at all. I have to use the kill switch on the inside of the firewall behind the clutch pedal to shut them down. I've looked in a couple of shop manuals and nothing there under troubleshooting. Could it be the microprocessor for the fuel? Any ideas? Thanks.

Butchart

Have located and found the problem It was the fuel pump sending relay located on top of the drivers side fender well. I unplugged it and plugged it back in again and problem went away for now. Probably will have to get another relay. It shuts off the current to the fuel pumps when the ignition is turned off. So if anyone out there has that problem, look for the relay. Rather odd too, I have a Clymers and Chilton manuals for the F-150 and not a mention of that relay.

Butchart

I replaced the fuel pump relay just a few days ago and have found out my truck is performing better. I believe the faulty relay was causing some resistance and from that the fuel pumps were not getting full voltage...therefore lower fuel pressure to the fuel injectors...thus the poor performance especially pulling away from a stop.
So any of you have a similar problem, before you change fuel pumps, check out the relay first.