Fuel pump?

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Jul 5, 2010 | 01:14 PM

Hammerhead24

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Fuel pump?

I have a 05 f-150 stx with the 4.6, my truck runs fine unless I hold the gas on the floor, around 4,000 rpm it starts to rough, its like the fuel is being shut off then back on and will continue to do it until I let off, then sometimes during normal driving it will start missing, backfire through the intake then die...come back an hour later it will fire up and run fine. I did get three codes with my scanner...PO191 which was the fuel rail pressure sensor...then system too lean on banks one and two...i dont remember what the code numbers was for those 2 codes but i have been told that if the truck shows these 3 codes then it is more than likely the fuel pump...has anyone else heard of this? Any input on what to do would be appreciated, Thanks

Jul 5, 2010 | 01:44 PM

screwy

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From: Over Yonder, MN

First thing I'd do is replace the fuel filter, could be clogged up.

Jul 5, 2010 | 02:09 PM

Hammerhead24

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Its already been replaced, thanks

Jul 5, 2010 | 02:53 PM

screwy

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From: Over Yonder, MN

Next up I'd look at the fuel pump driver module, the casing on them is known to rust through allowing crud to get inside which can cause a number of fuel related issues. It's a small box mounted on a cross rail near the spare tire.

Jul 5, 2010 | 03:23 PM

Hammerhead24

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I have already replaced that as well, guess I should have put this in the first post...I have also replaced the MAF sensor, no change with anything I have replaced...

Jul 5, 2010 | 04:38 PM

60DRB

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From: East L.A.

Screwy hit the first two steps already. I had a fuel pump go that acted in a somewhat similar fashion. My experience with older EFI Ford fuel pumps is that I heard a loudish buzzing/whining from the pumps before/as they failed. One quit outright and the other would work at light loading, after I got up to cruising speed, but would act as you describe when asked for any load demand like acceleration. The issue you describe of working fine after a rest period still sounds like a filter issue possibility. The debris loosens and falls away from the element, and refills the filter folds when pressurized maybe...had that happen once in a Toyota a long time ago.

Jul 5, 2010 | 09:30 PM

Greg B

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I would check the pressure and volume of the fuel pump. It sounds like that could be the culprit. Usually when you get a P0191 code, it's the driver module. But it can be a pump. I kept getting that code on the wife's Taurus. After checking things out, it was the fuel pump. But on the Taurus the driver module is part of the pump assembly.