Intermittent Fuel Pressure issue - already addressed common problems...

[mattster03]

I've got a 2008 Explorer Sprort Trac Adrenalin (4.6L) that has a frustratingly intermittent fuel issue, the engine has 165K . Once every tank or so, I'll be driving along and the truck will completely lose all power. I pull off to the side of the road and while the engine is still running, it sounds like it's misfiring like crazy and eventually stalls, it throws a P0191 and a couple of lean codes. The odd part is it usually starts back up just fine after a few minutes and runs for another tank. I have replaced the Fuel Pump Driver (Dorman), the entire fuel pump assembly & the pressure sensor (Ford Motorcraft). I was able to catch it in the act a couple of days ago with a scanner tool that gathered some live data for me and it showed a fuel pressure of 11psi while it was sputtering on the side of the road and lean readings of +25-37 on both banks, happy to post the full data if anyone is interested, nothing else was super out of range.

This has been a great truck for me, but I'm at my wits end on this one. I'm supposed to tow with it and take the family on a big road trip next weekend, but starting to think I need to cancel. Is there anything I am missing?

 

[bdmaash]

guessing here
wire harness (ground connection to fuel pump driver module, fuel pump - a weak connection may look ok with meter when not in use)
changed filter?

 

[mattster03]

guessing here
wire harness (ground connection to fuel pump driver module, fuel pump - a weak connection may look ok with meter when not in use)
changed filter?

Oops, yes I forgot to mention, fuel filter was replaced as well. I am suspecting the wiring at this point as well. One thing that's on my mind is that I had some 3rd brake light leaking issues a number of years ago and I wonder if it got wet enough under my carpet to corrode a connector or something like that...

 

[Dsc]

To the OP, what did you find out?
I have a similar problem with my 07 4.0L. Runs well until warm/under load and then it stumbles and stalls. Shut in down and restart and all good for about 10 minutes and it repeats. First I time I had P0301 and P0191 code. Replaced plugs, wires and coil, then cleared codes. Road test did the same, but P0191 only code this time. I checked fuel pressure and I get 50 psi KOEO (cold). Starts and pressure is 30 psi fairly steady at idle.
I replaced the fuel pump, fuel filter and FPDM (Dorman) about 3 yrs ago. Truck has only seen about 2K since.
Any ideas?

 

[mattster03]

To the OP, what did you find out?
I have a similar problem with my 07 4.0L. Runs well until warm/under load and then it stumbles and stalls. Shut in down and restart and all good for about 10 minutes and it repeats. First I time I had P0301 and P0191 code. Replaced plugs, wires and coil, then cleared codes. Road test did the same, but P0191 only code this time. I checked fuel pressure and I get 50 psi KOEO (cold). Starts and pressure is 30 psi fairly steady at idle.
I replaced the fuel pump, fuel filter and FPDM (Dorman) about 3 yrs ago. Truck has only seen about 2K since.
Any ideas?

I finally gave in and found a new old stock Ford FPDM to replace the Dorman that I had put in about 2 years(?) prior. It's been about 500 miles without an issue. My working theory is that the Dorman unit is a POS that failed way too quickly. I'm still preparing myself to have it die on me again, but as the miles go by I am becoming more and more confident it was the FPDM. It's interesting that your replacement was a Dorman as well and you're experiencing similar trouble...

 

[Dsc]

Thank you for the quick reply.
I was originally thinking the FPDM might be the problem since it was the same code. However I want to do some more tests before replacing it again. The other part is the Fuel Pressure Sensor but that requires the intake removal and I am sure I will have more parts and problems to change it and don't want to just throw parts at it.
I do not know if you had the same experience but my FPDM plug was very hard to insert into the Dorman part. In fact, I first had no fuel pump power and had to really press it in hard to get a connection. If I have to remove the plug, I am sure it will be destroyed and I will have to replace.

 

[mattster03]

Thank you for the quick reply.
I was originally thinking the FPDM might be the problem since it was the same code. However I want to do some more tests before replacing it again. The other part is the Fuel Pressure Sensor but that requires the intake removal and I am sure I will have more parts and problems to change it and don't want to just throw parts at it.
I do not know if you had the same experience but my FPDM plug was very hard to insert into the Dorman part. In fact, I first had no fuel pump power and had to really press it in hard to get a connection. If I have to remove the plug, I am sure it will be destroyed and I will have to replace.

FYI, the fuel pressure sensor (for me, at least) was right out in the open... do intake removal. Two small bolts holding it into the front of the driver's side fuel rail... super easy replacement.

 

[Dsc]

FYI, the fuel pressure sensor (for me, at least) was right out in the open... do intake removal. Two small bolts holding it into the front of the driver's side fuel rail... super easy replacement.

You are correct for the 4.6L. Unfortunately I have the 4.0L which is more work.
I will report back on how this goes.

 

[jrford]

I had the same issue, lost fuel pressure and replaced fuel pump, fuel filter and FPDM (Dorman) in the fall. The stock FPDM had a large corrosion hole in it, surprised it even worked for a long as it did. Ran great all winter. Once it started getting warm out, it started cutting out after about 30 min of driving. Replaced the FPDM again (non-dorman) but also noticed the Ground wire was rusted up bad. My guess is the bad ground caused the FPDM to overheat. Running well so far.

 

[Dsc]

I had the same issue, lost fuel pressure and replaced fuel pump, fuel filter and FPDM (Dorman) in the fall. The stock FPDM had a large corrosion hole in it, surprised it even worked for a long as it did. Ran great all winter. Once it started getting warm out, it started cutting out after about 30 min of driving. Replaced the FPDM again (non-dorman) but also noticed the Ground wire was rusted up bad. My guess is the bad ground caused the FPDM to overheat. Running well so far.

I was able to remove the Dorman FPDM without destroying the plug. Like I thought the white part of the plug remained stuck in the FPDM. I was able to pry it out and put it back in the black plug. Just need to do the resistance and voltage checks on the plug, to verify specs.
I also was wondering about the ground which is two wires attached beside the FPDM mount. The bolt is quite rusted but the wires look pretty good, so was going to check the resistance between the wires and a good ground. Will have to grind off the bolt from the underside and then relocate the ground to a clean spot.
Right now I plan to buy another FPDM (Standard Products) from Rockauto and after that do a hard reset of the PCM (which I have never done).

 

[Dsc]

I've been slow walking this repair and here are the results.
Replaced the Dorman unit with a SMP FPDM. It is lighter than the Dorman but the socket for the plug was designed better, for me at least. The plug connected easily and "clicked". Still a China part but I did see my Ford parts site list a FPDM as available. If this would have been available 4 yrs ago, I would have started with it.
I ground the grounding bolt off and used a punch to remove it. The two wire lug was in good shape, just required a little wire brush clean. The bolt head was fairly corroded (pic attached). I cleaned the surfaces and put a new bolt in with a star washer.
KOEO showed 50psi and after starting pressure dropped slowly to about 29psi and then rebounded to steady at 30.5psi. Took it for a half hour drive with no issues.
It it solved, don't know. I don't use it all that much, maybe 700mi per year, so will see.