I honestly can't figure out whats wrong with my fuel pressure...

[fuelonempty]

It seems like everything I try to do to fix the problem only makes it worse...

It just keeps getting lower and lower. Now I'm at 19psi with the twin 255 pumps. and while cruising the psi just jumps all over the place (18-22PSI), until it boosts 11psi, the Fuel jumps from 22 to 50!

The L is constantly starving for fuel and air fuel ratio is -- at some cases.

I spoke to Dante a couple of times about it. I double checked the wiring, I even took the pumps out of the tank and put them in a bucket of gas and started the truck. They are both on! and no leaks. should I just give up on these things and get new pumps??

I can upload a vid if needed but you'll just see what I explained.


I'm dying to get into WOT, but I cant get a good tune with this everchanging fuel pressure.

(mods are in sig btw..)

EDIT: here's the fuel pressure on a good day..

 

[ViciousJay]

ok... so youve checked the wiring meaning? have you tested it to see if theres voltage? next is are you sure the line isnt plugged? bad injector? or possible a bad fuel filter? jsut a few common things to check! :beer:

 

[Kryo-Genik]

by chance have you checked your FPR?

 

[cthunder]

did you upgrade the y too? it may be crushed if it's still the stock one. Upgrade to a SS y. the other problem may be your FPR on the stock fuel rail is going south. It may be time to upgrade to billet rails and a better FPR.

 

[Derek@Amazon]

did you upgrade the y too? it may be crushed if it's still the stock one. Upgrade to a SS y. the other problem may be your FPR on the stock fuel rail is going south. It may be time to upgrade to billet rails and a better FPR.

yea check the Y if your still running plastic Y... also check the Plastic lines for cracks. a buddy of mine had a crack in his and would do the same thing.

if those both check out try a set of fuel rails with a known good FPR.

 

[fuelonempty]

Check the wiring as in all connections and voltages.. Also, I know that the Y is the weak part of the system, and it is ok.. all the lines front to back have no leaks at all.. Injectors are brand new, and so is the fuel filter..

School me on the FPR, how do I know its bad? and is there a way to upgrade it while keeping the stock fuelrails? I know if I upgrade the rails I need to do all the lines as well, correct?

 

[LINOGT]

Bad gauge or sending unit?

 

[Derek@Amazon]

Bad gauge or sending unit?

actually thats a great idea... ive never seen one of the autometer units last very long

 

[I'D WIN]

Any fuel pressure problem is always hard to diagnose through the internet.

I would check the resistor behind the front bumper above the heat exchanger.

If that is GOOD then I would jump the high low relay under the hood. When jumped, what does your fuel pressure do?

If that DOES NOT change anything, I would be leaning towards a fuel leak somewhere in your system.

Before I go on and on, check the above and report back brother.

 

[Schmuckingham]

After watching the vid i would say gauge, jumps in puel pressure like that usually denote drastic A/F changes

 

[FordFanStan]

Khalid,

First key on your ignition without starting your your truck. What does the fuel pressure read? Does it hold there for several minutes or does it bleed off? If it bleeds off at all then that is your first sign you have a fuel leak, either externally or internally.

Also, grab another fuel pressure gauge and sending unit and hook it up to the fuel rail temporarily utilizing a wye ("Y"), that is one quick way to determine if it is your gauge or sender.

Like Martin also said, check your resistor. Also you can check what your fp is reading when your relay under the hood is jumped. Then remove the vacuum line to your fp regulator and see if it fluctuates from what is was, with the engine running.

What was the voltage to your pumps when you checked? FFS

 

[fuelonempty]

At start, the pressure starts at about 20 psi, then slooowly climbs notch by notch to about 30psi.


Could it be a power issue??

Today I was sitting outside a friends house, with Max A/c on, lights and fog lights, my soundsystem was on, and I was putting up the windows. when I did that the FP jumped to 40psi. It did this like 8-9 times, and only at idle, not at driving speeds.. I have a vid of that too if you guys need it....

But I tried to do it when I got home but it wouldnt do it anymore.

Stan, I dont know what the voltage was, but my mechanic told me that they were fine.

I know it isnt the guage because I can feel the truck bogging out when the pressure drops. Its was running even worse tonight. It got as low as 17psi!!!!! with an A/F of 17 18 and -- at idle!

 

[bgstew6]

actually thats a great idea... ive never seen one of the autometer units last very long

Mine been running great for 3 years....:shrug:

 

[Lord Tauk]

Yeah my FP sender has worked great for a long while too. Maybe mine was made on a Wednesday.

 

[BriteRed20s]

I think you may be able to order a new stock fuel pressure regulator as it is retained by a large circlip. This may not work as Ford likely does not sell the FPR as a separate item and you will have to buy the whole setup. Or you could order a Ford fuel rail setup for a 97 and an Accufab fuel Pressure Regulator as this device is adjustable and mounts/bolts directly to the fuel rails in place of the OEM regulator.

If you have access to the pumps, you could plug off the return line emptying into the tank through the fuel hat and see what the fuel pressure goes to at key on and then turn the key off and see how long the pressure is maintained.

 

[Derek@Amazon]

Mine been running great for 3 years....:shrug:

WTF longgest ive seen one last was like a year

 

[fuelonempty]

So I cant figure out whats causing this problem.. Its really frustrating considering I spent all this money and still can't drive the truck! with the fuel pressure so low now the truck barley idles, and boggs out when any fuel is given..