Post Preview: Hello about two months ago i bought a 1987 f150 with the 300 six. The truck needed some body work which i am very good at but ran great. The previous owner had removed the rear tank but other than those two issues it appeared that the trucjk was mint. well i drove it for a week and it started to have some issues.
After running the truck to operating tempture and shuting it down it would not started. So i took it to a shop i thought i could trust and needless to say 500 dollars later it was not fixed. So the problem got worse driving home from work it dies at about 65 and won't start have it towed, To a differnt shop i know will not screw me.
NO Fuel pressure or Spark check all the fuel pumps and relays they are fine change the ignition module and got spark. Still no fuel pressure the guy the shop is stumped shop owner comes out unplugs a relay to double check it. When he plugs it back in pressure. buy the time he gets to the cab to try to start it no pressure he is about to give up. He knows there is a short somewhere but cannot find it anysuggestions is htis a common problem i am about to push this truck out into traffic i am at m y witts end thanks guys

 

Technically, it's not a "short" - it's an "open" circuit. That old Ford-type relay was never reliable, but any reasonably qualified mechanic should know how to put a jumper wire across the socket to make the pump run, or at least to run power straight to the pump to see if it works.

If the relay or its socket turns out to be the problem, DON'T buy another one like it - get a Bosch-type from there or even Wal-Mart. They're MUCH cheaper and more reliable. Ford, Porsche, BMW, Jaguar, Land Rover, Volvo, and even some oriental makers used them because they're so good.

If they can't figure it out, get a Haynes manual and read it. After spending $12 and a few hours reading, you'll be more qualified than they are.