I got an 87 f-150 5.0 efi i put a new motor in about 3 years ago and been having problems since first was a bad hesitation, found a mud dobers nest in the vacumm lines to the map sensor and that fixed that, but now it will runn about 25 mins at idle with 35-40 psi fuel pressure then the pressure will drop to zero.
I've installed A new Motorcraft High-Pressure Pump on the Frame, and a new dephi pump and filter in the Rear Tank, New inline filter, but it will only run about 25 mins then stal. Let it Set for about 10 mins and it will fire right up, it has new fuel pressure reg, new fuel pump relay, new coil, and ign. module, I'm at wits end now with it, i was told i need to replace the front tank pump also. i'm tired of throwing money at this truck and want to drive it again. i've only put 100 miles on it in 3 years.


Thanks For any help

truckdude239

 

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guys i finnalyy have after a couple of years found my problem, the fuel tank selector switch when on the rear tank had power going in and none going out, when on the front i had power in and power out, installed a new selector switch tonight and clicked it to rear tank truck started right up, and the rear pump buzzed to life (which it wasn't Before) truck now runns great with no problems drove it about 5 miles with no issuse. the high pressure pump no longer whines i think it was pulling fuel though the back pump even it it wasn't running making it run harder.

Thanks for all the help Truckdude239