92 Fuel pressure problem
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From: Calverton
92 Fuel pressure problem
I had another thread going on for this problem, but it was titled indicating a code solution was sought, it is a fuel delivery problem. I determined that this is a fuel problem, and maybe someone with knowledge of fuel systems can help me out here. Link to original thread:
https://www.ford-trucks.com/forums/1...led-motor.html
.
Well the truck finally repeated the problem today. I've been driving around since the problem first occurred with a fuel pressure gauge hooked up to the rail. When she died I looked at the gauge and it was at 30 psi, 5 psi below minimum spec. I waited a half hour turned the key to get a reading, the gauge said 32 psi, again this was engine off. It was enough to start her, so I continued to the gas station. After fueling, I took another reading engine off, she was at 40 psi, which is normal. So now the question, dose this indicate the fuel pump motor is getting to warm and dragging, and not able to deliver the needed 35 to 45 psi?, or possible something else is going on here. There is no pump on the frame rail, did the 92's have their fuel pumps located only in the tank's?
https://www.ford-trucks.com/forums/1...led-motor.html
.
Well the truck finally repeated the problem today. I've been driving around since the problem first occurred with a fuel pressure gauge hooked up to the rail. When she died I looked at the gauge and it was at 30 psi, 5 psi below minimum spec. I waited a half hour turned the key to get a reading, the gauge said 32 psi, again this was engine off. It was enough to start her, so I continued to the gas station. After fueling, I took another reading engine off, she was at 40 psi, which is normal. So now the question, dose this indicate the fuel pump motor is getting to warm and dragging, and not able to deliver the needed 35 to 45 psi?, or possible something else is going on here. There is no pump on the frame rail, did the 92's have their fuel pumps located only in the tank's?
Fleet Owner
Joined: Oct 2005
Posts: 20,785
Likes: 1,751
From: Kentucky
You have a single high pressure pump in each tank. If the fuel pressure is dropping then I would suspect the Fuel Pressure Regulator. If the pressure drops on each tank, it is either a weird fuel filter problem or more likely the FPR.
Another thought would be the fuel pump relay getting resistive when hot. There would be more of a voltage drop across the contacts therefore less voltage getting to the pumps. It is a long shot, but a possibility.
Start with the pressure regulator, then go from there.
Another thought would be the fuel pump relay getting resistive when hot. There would be more of a voltage drop across the contacts therefore less voltage getting to the pumps. It is a long shot, but a possibility.
Start with the pressure regulator, then go from there.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Check that the pumps are getting a steady 12v first, look for corroded or frayed wires at the relay and inertia switch. You could take the monitoring a step further and wire in a volt meter at the tank to see if the voltage drops when the problem occurs. If it doesn't then that would tend to indicate a failing pump or clogged fuel filter, and while the FPR could be bad they generally don't fix themselves after going bad so that's not as likely.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
Does not sound like a fuel problem.
Sounds more like an Ignition problem.
It is normal for the fuel gauge to drop to about 30 PSI as the engine dies.
The engine should keep running down to about 28 PSI.
I would look at the PIP sensor or the TFI module.
After reading your other post.
You did not seem to have a code for the fuel system or PIP so I would guess a bad TFI Module.
Sounds more like an Ignition problem.
It is normal for the fuel gauge to drop to about 30 PSI as the engine dies.
The engine should keep running down to about 28 PSI.
I would look at the PIP sensor or the TFI module.
After reading your other post.
You did not seem to have a code for the fuel system or PIP so I would guess a bad TFI Module.
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Posting Guru
Joined: Dec 2009
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From: Calverton
Does not sound like a fuel problem.
Sounds more like an Ignition problem.
It is normal for the fuel gauge to drop to about 30 PSI as the engine dies.
The engine should keep running down to about 28 PSI.
I would look at the PIP sensor or the TFI module.
After reading your other post.
You did not seem to have a code for the fuel system or PIP so I would guess a bad TFI Module.
Sounds more like an Ignition problem.
It is normal for the fuel gauge to drop to about 30 PSI as the engine dies.
The engine should keep running down to about 28 PSI.
I would look at the PIP sensor or the TFI module.
After reading your other post.
You did not seem to have a code for the fuel system or PIP so I would guess a bad TFI Module.
Thanks for the help...does a TFI cool off and cure it self, till the next heat up?
Cargo Master
Joined: Oct 2008
Posts: 2,308
Likes: 1
From: Elyria, OH
yeah even if you take a bad TFi to the parts store and have them check it they will tell you its in good shape lol. The thing is they go bad when they are hot and they have no way to be able to heat them up at the store so they only test it cold.
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Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
I take it your fuel pressure gauge is doing something like the one in the attached FLV video.
Just click in the image.
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Just click in the image.
/
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Posting Guru
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From: Calverton
No thank god...ignition off 40psi-running 34, steady. I just bought a TFI and will be installing soon. That's if I figure out what type of screw head they got in there, holding her down. lol
Cargo Master
Joined: Oct 2008
Posts: 2,308
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From: Elyria, OH
They have them at advanced auto or autozone. Its an ignition module removal tool
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Posting Guru
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From: Calverton
Yea I heard that, when I asked them over there, they looked at me like I was nuts lol ...I'm just wondering the head style and size, my friend says its a 5mm standard 5 sided socket ground down for side clearance. Mine is on the drivers side fender.
Fleet Owner
Joined: Oct 2005
Posts: 20,785
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From: Kentucky
It's a 7/32 (5.5MM) thin wall socket. Ryan has some info here: Ford Fuel Injection » EFI Tools
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Posting Guru
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From: Calverton
It's a 7/32 (5.5MM) thin wall socket. Ryan has some info here: Ford Fuel Injection » EFI Tools
Thanks ria!!! I have a couple of them, I'll grind one down a bit.
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