Hello , I'm new here but I've been driving ford trucks forever. I have a 92 f150 with a 4.9 six cylinder. Yesterday I accelerated onto the highway and she started bucking. If I eased it to her she finally reached 55. I got it home and put in a fuel filter. Nothing changed. At idle, the motor revs up and down consistently. This morning it started and stalled. I turned the key on and listened for the fuel pump. It sounded weak and whiney and it didn't shut off after a few seconds like it should.
I talked to a mechanic friend who is a Ford fan. He said the fuel pump was weak and couldn't pump up enough pressure.
I put in another fuel pump (not fun) and its sounds stronger but theres no improvement and the pump stays running when I turn the key to the first position. That's not supposed to be happening. I'm in a real jam as that's my work truck and I need money badly.

This story has one more twist. I have a 96 Explorer in the yard that I'm about to scrap. It runs but it's ragged out. Just out of curiosity, I dropped the tank and removed the pump and it was identical looking. It was put in recently so I used it. Was that a mistake? Do any of you recognize these symptoms? Any help would be appreciated

 

Have you checked your codes?

 

No but my friend and neighbor is supposed to bring his to me tomorrow. I forgot to mention I checked the fuel pressure and it was near 80. That's kinda high is it not?

 

At the rail?
Is your return line clear, maybe try looking it over for kinks or crushed spots.

 

The fuel pump doesn't cut off by pressure it has a timer in the ECM that determines how long it runs. If it doesn't shut off after a few seconds after you first turn on the key either you have something going on with the timer or you have a ECM or a pump relay sticking.

Yeah the pressure should be 50-60 PSI KOEO. Sounds like you either have a blocked return or a bad regulator.

 

It was 80 at the shrader valve. I'll trace that return line tomorrow. Thanks