I just bought a '91 f150 with 140K, the previous owner replaced the fuel pump for me. Drove it home, next day wouldn't start. He suggested "priming" the pump by removing the FP relay top and with a wire, connecting the 2 elect. tabs so the fuel pump ran continously for a a few seconds, then try it. It worked--so I put some dielectric grease in it, started/ran fine for the past 3 days and through a 100 mile trip yesterday-this morning I could not hear the pump come on so i "jumped" it again and let it pump for 10 sec, reconnected the relay top, then i could hear the pump come on when I tried starting it-engine would fire briefly (1 sec-different than the first time when i got nothing) but would not run no matter what this time, but I did notice it firing for a second most times I tried. He claims he called the fuel pump manufacterer and they said there is a check valve in it so it should never need to be "primed"..my question is, could the fuel pump relay be hot /cold sensitive (seems like it worked always when the temp was 80 outside, not when it was 45 this morning) and why did "jumping" it work before and not now, even though afterwards i could hear the pump come on when starting it? I plan to buy a new FP relay this afternoon, should I replace the EEC relay as well? ..thanks for any opinions on this!

 

I will be replacing the FP relay and EEC relay this evening, and will post the results!

 

The PO is an idiot. All you did was complete the circuit to hotwire it. When you turn the key forward, the pump will prime the system up by itself no need to jump anything. Do you know how long it's been since the fuel filter was changed? Did he show you a receipt for the purchased fuel pump? Any fuel leaks anywhere?