Ford mechanics, I need help!!

[syoungs]

Bought a new truck (used) at the end of November, and it's been nothing but a problem, everything on it is great, but I'm having problems with intermittent low fuel pressure, low enough the engine stalls, sometimes while driving, others while parked.
 

05 f250, 3v v10. Fuel pressure runs 39-40# at idle, but will randomly drop down to 3-5#, sometimes at idle, sometimes while driving, which causes the engine to stall. Most of the time it will not restart right away, sometimes it will. letting it sit for 5+ hours and it almost always fires right back up.

I've replaced the fuel pump, fuel pump driver module, and fuel rail pressure sensor. Still having intermittent problem though. Only code is po191, fuel rail pressure sensor .

While working and monitoring pids I noticed the voltage jumping around some, from 13.3-14.2, most times when the truck stalls, voltage is down to 12.2
New alternator is on the way, current one tested bad, new battery is installed. Running Sans alternator, with fresh, new, battery, truck will still stall, at around 12.2-12.5v.

Problem seems to be related to the weather, if it's cold and wet, it happens. Haven't had it happen on a dry day yet.

Anybody have any ideas on where I should start? Gonna start looking at wiring to see if I have a bad wire somewhere under the truck this weekend. Could it possibly just be the crappy electrical system that was causing it?

Thanks in advance!

[cbond3318]

I have the 03' , V10, have you changed the inline fuel filter nearest the tank?

Mine had very similar symptoms , same code thrown , over the coarse of 2 weeks and it was the filter...I never was checking pressures and voltages though. Just figured I'd start at the easiest cheapest part....

[JDHasty]

Does it have a second, low pressure, fuel pump in the tank?  That can cause issues when it is going out because the high pressure pump needs head pressure to operate correctly. 

[syoungs]

Oh yeah, new fuel filter as well.

It's a gas rig JDHasty, only the one pump in the tank, which is new.

[92xj]

Check and clean all ground wire connections. I've seen bad grounds cause all sorts of weird issues. It's a real easy and cheap starting point in the chase and 75percent of the time a main cause of issues.

[syoungs]

Cleaned the rear ground, and main grounds, I need to dig around and find the rest of them though, actually forgot this was on my short list of to do's!

[Zardoz]

Check and clean all ground wire connections. I've seen bad grounds cause all sorts of weird issues. It's a real easy and cheap starting point in the chase and 75percent of the time a main cause of issues.

Kinda related. Years ago my Ford would just quit. After changing a lot of parts and not fixing the problem, I discovered by chance the problem was caused by faulty intermittent connections in the wire connection modules due to corrosion. I disconnect all connection points and cleaned them with a modified finger nail file board. Put some new electrical grease in the and problem solved. The connections all looked good because the corrosion layer was hard to see.   

[cbond3318]

There is also a Fuel Pump Driver Module that can be potentially shorting to ground during wet conditions. My only experience beyond what I have fixed is the extensive online troubleshooting. Those type issues can be frustrating ghosts !

[cbond3318]

I kind  of have the thought that if it is anything outside of the isolated fuel delivery system, you would be showing more than the one code.

[syoungs]

I kind  of have the thought that if it is anything outside of the isolated fuel delivery system, you would be showing more than the one code.

This was my thought as well, I do randomly get a code for the evap canister not being able to bleed pressure or something along those lines, I've seen that code one time, cleared it, cleaned up the EVAP system and hasn't been back.

The driver module is new as well, if I can catch it while it's throwing low fuel pressure, I'm hoping to test the supply and ground to the pump, if those are in spec, maybe I'm fighting a bad fuel pump or bad connections in the tank. Really regretting selling my last truck!

[Mark Brenckle]

I had an old Nissan that had a similar issue. Never did find the cause. I wired the fuel pump to my running lights and that solved the problem, just had to remember to turn my lights on to drive it...

[huntnphool]

@jackelope @coachcw

[syoungs]

I had an old Nissan that had a similar issue. Never did find the cause. I wired the fuel pump to my running lights and that solved the problem, just had to remember to turn my lights on to drive it...

Did the exact same thing on a old beater Subaru that I had years ago, won't work on this though, it's a returnless fuel system., No regulator in the fuel rail, regulates pressure by turning the pump on and off basically.

[yum tag soup]

The correct fix for this is to sell it and buy a dodge 

[Mudman]

Its electrical.  Alt. battery connections broken wire? PCM??  Gonna be a beach to find.