So, I just purchased a refurbished ECU from AutoComputerExchange.com after finding out the circuit board on my original ECU burnt up(was really strange, the truck stalled out while I was driving and then it wouldn't start, thought is was the fuel pump at first, but after some diagnostics, discovered two burnt spots in the circuit board of the ECU). The refurbished ECU was programmed specifically for my truck's VIN(including engine size etc.). I plugged the refurbished ECU in and the truck still won't start, and the fuel pumps continually prime. Any ideas??? My only guesses are the new(refurbished) ECU or fuel pump relay???

My truck specs:

94 F150 XLT Supercab 4X4

5.8 V8 EFI(351 Windsor)

~165,000 miles

Thanks,
Jason

 

You have a bad replacement computer (PCM). Any time the fuel pump stays on continuously like that it's either a stuck relay or the PCM is bad. It's usually the latter.

 

Probably is the ECM, BUT, I had a sticking fuel pump relay recently on my truck (I had to bang on the relay to unstick it). So both can happen.

 

I'm having a similar problem myself. First had it happen about a year ago, front tank randomly cut off, then wouldn't cut back on. Swapped to the back tank and had no problems. A few weeks later, the front tank worked again. IT would then begin to bog down and eventually die again on occasion. Last week however, had it on the back tank, which had always been reliable. Now it's doing the same thing, and won't even start.

The fuel pumps are constantly primed, and the engine will crank fine, but not start. Had the entire fuel system examined, and reported back that all the filters and pumps and pressures were good. The only info they returned to me on the electronics was that the PCM has water damage and several corroded, burnt out components. Is this the likely culprit, or should I be looking for the Fuel Pump Relay? If so, where IS the relay exactly, and how do I test it?

 

Turn on the key and with the fuel pumps running pull the fuel pump relay out and if drops out as you pull it out and clicks again and the pumps start back up it is more than likely the PCM Computer.

OR you can swap the fuel pump relay with the horn relay.

OR if the fuel pumps turn off and on with the key it is more than likely the PCM Computer.

The fuel pump relay is under the hood on the drivers side in the engine compartment relay/fuse box:




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