Ford Explorer Fuel Pump Relay

Concerns Contributed by Tom Carroll

Several colleagues and myself own Ford Explorers in the 1991 to 1992 range and have experienced similar problems as shown on your page. In addition, we all have experienced these problems:

1) Fuel level sensor failure: years 5 to 6 (around 70K miles) 4 out of 4 Explorers experienced this problem. There's something wrong with this sensor.

2) Fuel pump relay failures (around 65-70K miles) 1 case where relay failed open. No fuel. 1 case where relay failed closed. In this case the symptom first showed as engine dieseling in hot weather. The relay was sticking at first staying on for up to 10 to 15 seconds after turning of the ignition. Our local dealership could not find the problem. You can listen for the problem. Finally, the relay failed closed, with no dieseling effect. This drained the battery and left it dead. Again, the local shop could not figure it out. They simply said the battery died. I had told them that I heard a clicking sound from near the fuse box behind the battery.

Further Comments and an Emergency Fix

I had/have same problem with truck dieseling as described which is advertises an obvious problem (but what; took awhile) and the battery drain which is the silent killer. The tip off is if you can still hear the fuel pump by the time your feet hit the ground upon a normal exiting of the vehicle, there's a good chance your relay is sticking. The following procedure is not a fix (get a new relay), but might help if you're on a camping trip, or don't have time to change it. Under the hood, on the battery side (for my 91 anyway) find the fuse for the fuel pump relay. If you are truly having the problem described you can make the relay open and close by removing/replacing the fuse, or by connecting/disconnecting the battery because even with the engine off, there is still power to the relay which is cute, BUT IT'S WRONG! (stealing that quote from some cartoon, but I can't remember which one). Anyway, directly underneath the fuse is the relay. Wiggle it, fondle it, move it, play with it whatever you want to do with it in the privacy of your own garage, but seriously, that seems to help fix it for awhile. I suppose for safety you should disconnect the battery but I never do. If you're wondering why I haven't bought a new fuse it's simple. I'm too lazy, and will get to it soon.



A Possible Solution Contributed by Patrick McClanahan

I found that there is a series of wiring that goes from the drivers side firewall across the front of the engine block and around to the passenger side firewall and to the inside to an inertia switch (the switch under the carpet at the front of the inside firewall). The wiring in front of the block in the shielding developes a short causing the relay to short and snap the inertia switch constantly making you think that the fuel pump is going out or losing control of the guage and possibly tripping the inertia switch constantly. The solution is to rewire the harness at those points or just buy a new wiring harness from a Ford dealer for around $140. If you choose to buy this harness it will save a little headache on yourself as all it is a "plug and Play" vs. a wiring and soldering situation for those not into wiring! Hope this works!




Updated January 7, 1999

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