i have a 1991 ford f150 4.9 5 speed
the fuel pump stays on for a long period of time before start and at steady or low rpms it
sputters but you can throttle thru and runs fine. after driving for long period high idle.
have replaced every electric component, wires , plugs, cap, rotor, o2 censor, you name
it I have replaced it. what next
Check out: http://blog.chiltondiy.com/2012/05/how-to-tell-if-your-fuel- pump-needs-replacing/ I am a newbie at this & ever problem is seeming like a feul pump problem... That's what yours sound like to me. That website is a great troubleshooting guide
Might be fuel pressure regulator, Just because you say the pump runs to long, the regulator does so by creating a back pressure since it is located at the beginning of the fuel return line. usually! could also be a leak in your lines.the other thing to check is vacuum lines fuel pressure reg. is controlled by vacuum so a leak in the vacume lines could also affect this
I forgot the other obvious one is fuel filter, has that been changed?
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