Fuel pump issue
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4wd Low
Joined: Mar 2024
Posts: 10
Likes: 1
Fuel pump issue
So I was driving today (1989 f250 xlt 7.5L) and previously when I tried the rear tank it would stutter and then stall, now when I was driving today I parked on a hill nose up and I was on the front tank which usually works, I started it up and it wanted to die then I started driving and it kept wanting to stall, I finally got on the highway and it ran fine the way home, I’m not sure what the problem is, I’m assuming I have two low pressure pumps one in each tank, two lines that go into an adapter to one line then to the high pressure pump then the fuel filter, I’m not sure if that’s accurate or what’s wrong, any help would be appreciated thank you
Cargo Master
Joined: Aug 2021
Posts: 2,258
Likes: 742
From: Maryland
When was the fuel filter last changed?
You need to check the fuel pressure at the injector rail Schrader valve. If the pressure is low,
then pull the vacuum line off the fuel pressure regulator and see if the vacuum line has fuel in it. If so, you need a regulator. ( You can check that vacuum line any time)
Possible causes of low fuel pressure, other than the frame mounted fuel filter or regulator are; failing fuel tank selector switch in the dash, dirty fuel pump grounds, which are near the washer bottle on a 5.0 (they may be at the same location on your 460), failing fuel pumps, corroded electrical connections at the fuel pumps and it's possible that the Dual Function Reservoir (aka fuel tank selector valve) is failing. But I would investigate it last. They're expensive.
You have two in tank pumps, then a Dual Function Reservoir on the frame, roughly below the driver's seat, then a frame mounted high pressure pump, then a fuel filter.
There's a thread on this forum on how to test fuel pressure and some parts stores rent the gauge. Do that first. Here's the fuel pressure test thread
https://www.ford-trucks.com/forums/1715944-how-to-check-fuel-pressure-on-1987-1997-gasoline-ford-trucks.html
You need to check the fuel pressure at the injector rail Schrader valve. If the pressure is low,
then pull the vacuum line off the fuel pressure regulator and see if the vacuum line has fuel in it. If so, you need a regulator. ( You can check that vacuum line any time)
Possible causes of low fuel pressure, other than the frame mounted fuel filter or regulator are; failing fuel tank selector switch in the dash, dirty fuel pump grounds, which are near the washer bottle on a 5.0 (they may be at the same location on your 460), failing fuel pumps, corroded electrical connections at the fuel pumps and it's possible that the Dual Function Reservoir (aka fuel tank selector valve) is failing. But I would investigate it last. They're expensive.
You have two in tank pumps, then a Dual Function Reservoir on the frame, roughly below the driver's seat, then a frame mounted high pressure pump, then a fuel filter.
There's a thread on this forum on how to test fuel pressure and some parts stores rent the gauge. Do that first. Here's the fuel pressure test thread
https://www.ford-trucks.com/forums/1715944-how-to-check-fuel-pressure-on-1987-1997-gasoline-ford-trucks.html
Thread Starter
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4wd Low
Joined: Mar 2024
Posts: 10
Likes: 1
So I’ve been driving it more and the issue went away at least for the most part, when I’m idiling it sometimes feels a little rough, the vacuum line on the fuel regulator doesn’t have any fuel in it, I haven’t been able to test fuel pressure because I’m poor and I’m waiting for my paycheck to purchase one lmao, but I will test as soon as possible
Hotshot
Joined: Jun 2015
Posts: 12,872
Likes: 2,445
Yes. Rent one for $20 or whatever. Return it and get your money back.
The original problem seems like it wasn’t picking up fuel when on the hill.
The original problem seems like it wasn’t picking up fuel when on the hill.
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