I have a 88 F-150 4x4 shortbed 302 duel tanks.... when you floor the truck it goes but then starts to sputter and lose power and will die... it is then hard to start... i have replaced the fuel relay switch the inline (frame mounted) fuel pump and the fuel filter... any ideas on what else could cause this and ways to test it...

i also lose oil pressure when the engine comes down to a idle after driving it has a new pump and i tested the guage so i know that works....

I was kinda thinking it might be bad in-tank pumps because the truck was sitting in a field with the tanks out it was missing the rear unit so i went to the junkyard and got the rear but the front semed to work fine... but i find it strange that it would be both

any ideas?

(and no putting a bullet through the engine and calling it done isn't a option)

 

Check the high pressure pump and the pressure regulator on the fuel rail to make sure you have enough pressure. If the HP pump sin't running properly it can cause those issues. Mine just had a dirty connector (not weather-proof at all) and it worked okay afterwards.

 

the HP pump is less than a month old so im am leaning towards the pressure regulator it loses fuel presure after you shut the truck off.


any ideas on the oil problem? i thinks its just a bad switch/ sending unit but i would hate to be wrong and bllow the engine and i cant really afford to just start replacing parts until it finaly works

 

Stick a mechanical oil pressure gauge on and test what your actual pressure is at. The factory gauge is nothing more than an on/off that signals oil pressure over 7 psi (I think) = normal or under 7 psi = L on the gauge.

Until you know what the actual pressure is, it'll be hard to decide what if anything should be fixed/replaced.

 

alright well i think ive figured out the oil...when i bought the truck it had a bad radiator and i over heated it to the point that it shut down and boiled over about 4 times (ya i know stupid me!) so i think i burned out the crank/ connecting rod bearings, i replaced the oil with some 20-50 and it drops pressure a bit at stop lights but does not fully lose so im alright with it for the time...


and the fuel problem seemed to fix its self i just hope it doesnt come back anytime soon

 

Try running 50% Lucus in the crank. When I run regular oil in my 1988 F250 (186,000) the oil pressure light is always coming on when the truck is hot at idle. With the Lucus the pressure stays up fine.

 

That Lucus is some good stuff. I had a Dodge Motor Home with a 360 in it, hardly any oil pressure at idle and would knock at about 3000 rpms. I substituted 1 qt of lucus and it was alot quieter and had more oil pressure on idle. I changed the oil with Citgo 15-40 no lucus and about 15 miles later I threw a rod.... I replaced it with a 318, still running good for a dodge....