[font size="1" color="#FF0000"]LAST EDITED ON 09-Feb-01 AT 02:24 PM (EST)[/font][p]Hello all, I'm fairly new to this board and to my truck and was told this was a great place to ask trouble-shooting questions.

I have a 1989 F-150 with the dual tanks and the 3 fuel pumps. I went to start the truck one day a few months ago and it wouldn't start. I replaced the fuel-pump relay, the dash switch for the dual tanks, and checked to make sure I had proper voltage to the external pump. One thing everyone says is that I should hear a good or loud buzzing/whirring from the internal tanks BUT,,,, I have own the truck for 2 years and have NEVER heard any sort of fuel-pump noise. I took off the external fuel pump, checked it and replaced it. As soon as I tried to start it, vroooom, it starts and drives just as B4. I thought I had fixed the problem. NOPE. The next day, the truck wouldn't start and the fuel pump was fried/not working. I replaced it 2 more times with the same results and thought that "maybe" the fuel pumps were bad from Autozone.... I went to PepBoys and bought one of theirs. I put it on and it started up just like nothing was wrong and even seemed to be running better. I let it idle for a long time, came back even a few ours later and it started right up with no problems; even felt stonger than B4. AND, I tried switching to both tanks. No problems from either tank, even after trying to start the truck after turning it off from each tank!
BUT, the very next day,,,, BAM!!! NOTHING.... The fuel pump is out again. I haven't changed this one as I am perplexed and at a loss. Is there something I am missing???? Could something cause the 3rd(external) fuel-pump to just go out after sitting overnight???? I don't have a fuel-pressure tester and am wondering about the fuel-pressure regulator. Please, help me.

Thanks, Eric

 

From a few hard learned lessons,I would like to suggest that you may have a bad/broken wire at the disconnect point of the fuel pump. Even though the covering of the individual wires is intact, the stranded conductor (wire)inside can have a break in it, especially right at the point of crimping to the terminal. If this is true, everytime or just about everytime you unplug and replug the connector while swapping the pump, you regain continuity because the break in the wire is touching the terminal after beeing shoved back together. One way to check is by wiggling and tugging and pushing on the wires and connection while someone else tries to start the engine. Also make sure that the terminals are fully seated into the connector and do not back up as they are plugged back together. If the fuel pump is dead, an ohmmeter should show "open" across the wires.
Good luck,
Phil

 

Eric, When you refer to the pump as being fried, is it actually burned up? Did you bench test the pump after it crapped out? It almost sounds like the pump is not shutting down when you shut off the truck. Could the pump still be running when the truck is off? Possibly running dry because the tank pumps are not feeding fuel to it and causing it to burn up? Sticking relay of some sort? I would check the power going to the pump with the key in the on position and with it in the off position. Good luck.

Jakegypsum // Ford fleet, soup to nuts.