2008 F250 6.8 FPDM

My 2008 F250 has been acting up lately. 3 years ago the FPDM failed, replaced it with a dorman 590-001, was all great until a few months ago.
Truck consistently starts, would cut out while driving, no fuel pressure, verified power to module, forscan shows the fuel pressure drop off and the duty cycle for fuel pull deman ramps up. Durring this there was no power delivered to fuel pump. Jumpering the FPDM I would get 75 psi fuel pressure on the fuel rail. I warrantied the module, and it had similar issues.
At this point I went further on diagnosing, found a less than perfect ground at the rear frame rail, completely rebuilt the ground in the circuit including tying in the shield for the fuel pump wiring, ohmed out the communication wiring for the FPDM, pump and pump wiring separately.
Confirmed the duty cycle demand to the fpdm was the same as the computer was requesting. The fpdm will shut off while idling in the driveway.
At this point it seemed like the dorman warranty part was doa, I installed a motorcraft fpdm. Everything worked great, idled for an hour no issues, drove around the block a few times, seemed fixed. After 35-45 minutes it cuts out.
I checked that the monitor duty cycle and it goes from 50% while everything is working to 0% when it shut off. The control duty cycle tracks what forscan is saying. FPDM is switching the 12v side to the pump, ground to the pump is good from the moment the fpdm gets power. Seems opposite of what I have seen online, tripple checked the wiring on the fpdm plug.
I have also changed the plug, wasn't sure if I was having bad connections.
Checked the circuit under load, fuel pump jumpered 100%, draws 9.8-10 amps, 13 volts across the pump.
I dont have a scope, just multi meters that can read duty cycle and hz.
When the fpdm cuts out i have confirmed that the voltage to it does not drop out.
I have been able to replicate this with the truck idling in the driveway.
I have not been able to watch the fpdm monitor duty cycle as the driver cuts out.
I have also checked over the wiring harness under the truck, dropped the tank and checked the connector, ran power from the battery to the output of the inertia switch.
Fuel pump ohms from .8-1.6, it seems to always read higher when the fpdm has shut off. Is the pump just tired?
Any help would be awesome.

Artstu, do you recall if any fault codes set during the stall? I figure with the FPM circuit showing 0%, or the fuel pressure not meeting desired, one fault or another would have shown up.

You said you can reproduce this in your driveway, right? In that case, I think I'd try jumping power and ground to the pump at the FPDM connector and seeing if the loss of fuel pressure reoccurs. If it does, the FPDM and the control circuits aren't the problem.

I don't recall if it's possible with this exact FPDM connector (WPT-903), but on some, you can simply use an ATM or Micro2 fuse across pin #2 + #3 and #4 +#5.

I will have to check, the exact codes, but low rail pressure and possibly loss of power to module, I will reset the codes and confirm without u plugging and checking anything.
The pump always makes 70-75 psi when jumping power and ground at the connector for the fpdm, even immediately after the module shuts down. I am going to double check the monitor circuit, I have seen they are sometimes low frequency and a multimeter can have a hard time picking it up as a duty cycle.
I will also upload a couple of logs showing what the pressure demand, control and rail pressure are.

Cleared and pulled the codes again after experiencing the drop in fuel supply. Didn't get a chance to confirm duty cycle on the monitor circuit.
P1233
P0191
From what I have read if I had a problem with the fuel pump or the wiring I would have a p1237.
attached a couple screenshots of what is going on one from initial starting, one when it cuts out. Durring both these situations I have confirmed that the control duty cycle is correct at the pcm plug and at the fpcm plug, both reading desired duty cycle plus or minus 1-2% at 150 hz and while everything is working I have 50% on the monitor pin.

Quick update. I ran dedicated 10 awg from the battery ground and power to the fpdm pins 3 and 5. Confirmed control circuit, matches ecu demand, monitor circuit has 50% while running, goes straight to 0%, 14v when it shuts down.
This is happening on both the brand new dorman part and the brand new motorcraft part. At a bit of a loss here, everything I have read still points to a bad fpdm, but I am leaning towards just putting in a new pump to rule that out. Not a fan of just changing everthing till it works.
 

Changed the pump, same issue, ford module only lasts for 5 min idling in the driveway now. I depinned the connector for the fpdm and tightened the tabs on each pin just to make sure it isn't loosing connection while running.
Restarting after it dies leads to shorter running times or no running time.
All fingers are pointing to a dead fpdm, just having a hard time believing it.

It has been about 3 weeks since your last post, wondering if you have found the problem? I am having the same issue with my 2006 Ford E-450 SD with 6.8 V10. I am at the same point as you were with your last post.

I too have been wondering if another FPDM fixed your issue.
I had to put 2 in my truck in a couple months time...

I've checked everything that I can, got a cheap oscilloscope and couldn't find any issues with the pwm from the pcm, confirmed that the monitor circuit is doing fine until it shuts down.
I even tried idling the truck with whatever fuel pressure was in the lines while the fpdm was running a light bulb instead of the fuel pump, it would still shut down.
at this point it looks like maybe my questionable ground wire wiped out the module. I might try and use a signal generator and simulate what the pcm is doing on the control circuit. It's possible I am missing something on the control circuit with my oscilloscope, it doesn't have much for memory to scroll back though. I have moved my ground location to somewhere I can actually see it and keep an eye on it, I will probably upgrade the wiring to the fpdm, similar to how the mustang guys do.
I will keep everyone updated, nervous to put another one in at this rate, but the only other option is put a regulator and return line in.

I finally called a Ford truck service center here in NC and spoke with a tech and told him my issue I was having. He asked me if I performed a Reset of the PCM after I installed the new FPDM. I told him that I did not. He stated that it is always a good practice to do it after a repair especially after replacing electronic parts so the PCM can relearn operating conditions. He also stated that it is always good practice to disconnect the battery while performing repairs to prevent injury or damage. A hard reset is disconnecting both battery terminals and shorting them together for a minimum of 10 minutes. He is also not a fan of aftermarket electronic parts.  Long story short I performed a hard reset of the PCM after I reinstalled the original FPDM and to my surprise it worked.  I'm up and running with no unexpected shutdowns in over 50 miles. So, for me lesson learned! (never hurts to ask for help) I'm into this repair for 3 FPDM's (because the original motorcraft part still works) and one Fuel pump. almost $600 in total and untold manhours. Now I'm not saying this will work for you, but it worked for me. If anything changes, I will update you. good luck!

Occams's Razor - The simplest solution tends to be the correct solution!

Good to know on the hard reset. I will have to give that a try. I have definitely had the battery disconnected for long periods of time throughout the process. Hopefully the fix is permanent for you. I have had mine be working for 1 hr of idling and then 2 hrs of driving and no issues, on a colder day, then 5 minutes on a warmer day. Then 10 minutes of idling in the driveway on an even colder day than the first day. Each time I have been able to confirm my control pwm signal either while it died if it was idling or right after while it was running on fumes and it looks great, perfect 150 hz, 46-48% duty cycle just like the pcm is demanding. 

That's exactly how my F150 acted. Just like the one Paul put on you tube not too long ago. Would run perfect for days then suddenly I'm coasting through traffic on the highway. Die six times in the driveway, but once my test equipment is out, runs for days. All the bidirectional tests worked exactly as they did for Paul (including the way the pump sounds while changing the PWM).
I put a second Dorman FPDM in it probably 6ish months ago and has been perfect since.
I hope the hard reset is a permanent fix for you!

Thanks for the info! I tested a my old driver on the bench with a pwm generator and a mosfet module to simulate the switching the pcm does, works great for a few minutes lighting up a headlight, then dies, just like it does in the truck. I got a new ford fpdm today, going to run a dedicated ground to the battery and a power wire switched with a relay off the inertia switch to eliminate any voltage drop.