VTXman196

I am having an issue with my 05 FX4 5.4L. this is gonna get complicated so hold on tight. about 5 months ago I had the typical "sputtering/loss of power" associated with the corrosion on the FPDM. I replaced it (with the stand-offs) and ran fine for 5 months. I recently had the "sputtering/loss of power" again, this time getting a P0191 code and only that code, fuel pressure in freeze frame was 10 psi. going on the "it cant possible be the new FPDM" assumption, I replaced the fuel filter (it was nasty) and ran fine for a couple of days. then.... "sputtering/loss of power" is back and even worse and only the P0191 code again (pressure read 11psi) (no other codes). I tested the fuel pressure sensor and even though sensor tested as good, I replaced it anyway. a couple of days later....you guessed it..."sputtering/loss of power" (pressure 10psi) and only the one code again. now I am beyond pissed. i shoot every wire in the system for power and ground (granted, I do not have an oscilloscope or even a fancy meter....just a basic one) I now begin to think that the fuel pump itself may be failing (albeit intermittently) and considering that the pump is the only other thing in the system......I changed it too....the whole assembly, not just the pump or just the strainer....the whole thing. (what loads of fun that was!) can you guess what has happened after about 2-3 days? yup! you guessed it..."sputtering/loss of power" and just one code P0191 (9psi). now I'm livid! so now the "it cant be that brand new FPDM" thought gets replaced with "what if that new FPDM is bad?" so I remove the module ( and shoot every wire again, check every connection....even the ones under the drivers door on the frame) and take it back to the parts store for warranty replacement. I installed the new new FPDM and today is day 3 driving with no issue since then. meaning its due to happen again today. my question is this: has anyone else had this problem to this degree? what other causes (if any) could there be? since the issue seems to happen at about the same time the EVAP test should be run, is it possible for the EVAP system to pull such a vacuum on the tank as to overpower the pump but not throw a single EVAP code( i know there are at least 6 possible EVAP codes) i ask that question because the EVAP system takes a few days of running/cooling off before it will run its testes and I know that my truck has not run those EVAP tests as of arriving at work this morning because my OBD2 says so( I have been running with my OBD2 plugged in so that i can monitor fuel pressure) I know the truck can create enough vacuum to deform the tank but it would have to throw several codes....wouldn't it? please, any help would be very much appreciated. thanks

Bobby patterson

Did you ever figure out the problem?