low fuel pressure
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5th Wheeling
Joined: Sep 2016
Posts: 42
Likes: 3
low fuel pressure
1995 f250 5.8. i get a constant 17psi whether at idle or revving the motor. will not stay running without pressing gas pedal. pressure will hold in the gauge so it's not bleeding off anywhere. what should i check? thanks.
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
one or two fuel tanks? If you have 2 fuel tanks and the fuel pressure is low on both of them, then I would suspect your regulator.
If you only have one tank, or your fuel pressure is only bad on one tank, then I would suspect your fuel pump.
Heres a procedure I wrote regarding ford fuel pressure. https://www.ford-trucks.com/forums/1...rd-trucks.html
If you only have one tank, or your fuel pressure is only bad on one tank, then I would suspect your fuel pump.
Heres a procedure I wrote regarding ford fuel pressure. https://www.ford-trucks.com/forums/1...rd-trucks.html
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5th Wheeling
Joined: Sep 2016
Posts: 42
Likes: 3
it's dual tank and i forgot to mention that i changed the fuel filter. so i went to look at the fuel pressure regulator and noticed that the vacuum line on top had been chewed through. disappointingly when i spliced it back i had the same issue.
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
Have you checked your fuel pressure after the FPR change out.
Connecting the vacuum line to your FPR shouldnt make any difference because your fuel pressure is too low to open the regulator.
Connecting the vacuum line to your FPR shouldnt make any difference because your fuel pressure is too low to open the regulator.
Hotshot
Joined: Jul 2020
Posts: 10,453
Likes: 2,630
From: Near Salt Lake City
Both of your in tank pumps should put out 40 lbs
Check the pressure out of both at the crossover valve and then at the fuel rail
Should have 40 lbs both places, both tanks, until the regulator takes over
If you have 17psi out of both tanks, all of the sudden, your crossover valve may be at fault
That is why you want to check the pressure on both sides of that valve (thru a new fuel filter up front)
At least you can still get a new crossover valve for the newer ones 1990+ like yours
I doubt both tank pumps failed at the same time
It is common for the rubber hose on some of the in-tank pumps to fail and cause low pressure
Check the pressure out of both at the crossover valve and then at the fuel rail
Should have 40 lbs both places, both tanks, until the regulator takes over
If you have 17psi out of both tanks, all of the sudden, your crossover valve may be at fault
That is why you want to check the pressure on both sides of that valve (thru a new fuel filter up front)
At least you can still get a new crossover valve for the newer ones 1990+ like yours
I doubt both tank pumps failed at the same time
It is common for the rubber hose on some of the in-tank pumps to fail and cause low pressure
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FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
There is no "crossover valve" in the fuel system of a 90+ gas pickup, in fact the only thing inline between the tanks and engine is the fuel filter.
The FDM inside each tank contains check valves the are supposed to prevent crossflow between tanks, but these get contaminated and leak and some replacement modules apparently don't contain check valves or have poorly designed valves that don't work, and that results in the active pump filling the other tank and low fuel pressure problems.
The FDM inside each tank contains check valves the are supposed to prevent crossflow between tanks, but these get contaminated and leak and some replacement modules apparently don't contain check valves or have poorly designed valves that don't work, and that results in the active pump filling the other tank and low fuel pressure problems.
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