fuel pump

i have a 94 ford explorer. sometimes when i turn the key the fuel pump doesn't come on. so i thought it might be the inertia switch, so i unplugged it and plugged it back in. after that the fuel pump came on when i turned the key and the truck started fine. a few days later the same thing is happening. what is causing this and how do i fix it. :banghead:

Never assume too much. The inertia switch is certainly in a location that can get corrosion on the connector. If you don't see an obvious reason for the failure, it could be coincidence. Relay and pump problems are more common. Sometimes the best thing to do with an intermitant like this is to wire in a couple small lamps to verify power reaches several key locations. The act of touching wiring can sometimes make a circuit work. Without lamps, the diagnostic process can take months. I have a small plastic box that I can attach to the dash with four small LEDs just for this purpose.

I had the same problem with my '96 explorer. After much troubleshooting, the intermittent problem became hard and was traced to a bad PCM power relay. Replaced the relay and have not had a problem for 3 weeks now. Hope this helps you with your problem!

I had the same prob with engine not starting (never quit while running). Changing the relay worked and have not had that problem since. Those relays have been a source of numerous problems for me. It is not suprising as it gets quite hot in that relay box. Good Luck,

John O.

I forgot to mention, it was two relays that were involved on my 94 explorer, the fuel pump relay and the PCM Power relay. I first changed just the fuel pump relay, but the problem persisted. I then noticed that the PCM relay was also in the loop, and when I changed it too, BINGO.

John O