6.4 dies while driving. Starts up again and dies. P0625

taterthedog · Aug 1, 2023

Hi. Been a while since I’ve Been on here. Just wondering if anyone else has run into this problem. I’ve got an 08 F250 6.4 automatic. The other day I started it and backed up to my trailer. It died without any symptom. It would start up again after a longer crank for about a second and then due again. There were codes p0625 for generator circuit and one for fan speed I think. They didn’t come back when it wouldn’t start. I hooked booster cables to another truck to see if it helped. No difference. After a bit, it fired up and ran great, lots of power, no symptoms. Hooked to the trailer and went on. About a week later it died driving through town. Acted the exact same way. I eventually got it going after looking at it, wiggling wires, etc. Ran great all the way home, no sputtering, spinning tires on demand. Been sitting in the driveway since. This time only code p0625 present.

Anyone have a similar experience? I’m trying to get to the bottom of this issue before I use it again. I have a new Ford alternator to go on it. The one that’s on it was from Napa and doesn’t charge at idle. Could this cause it to stall?

For info, mods on the truck are: IH pistons, o-ringed heads, headstuds, camshaft and valve train, ported intake, No emissions, bigger atmospheric turbo, built trans. SCT tuner with Innovative Diesel tune (extreme x), Western plow. I’m sure there’s more. It’s been running this setup without issue for years.
Thanks for any help.

Hazzy · Sep 6, 2023

if it cranked over after stalling it would not be the alternator. next time it stalls you can check fuel fressure on top of the fuel cooler if you have a 30 psi tire guage should be 3 - 10 psi. mine had an airlock in it only produced 2 psi . i turn key on to start fuel pump and bleed air out of schrader valve on top of fuel cooler then it started and up to 9 psi. and theres some solenoids in the high pressure oil circut that could be the problem...

taterthedog · Sep 23, 2023

I changed the alternator and it was good for a week or so. Then it died just like before. Seemed to be affected by wiggling wires under steering column, but couldn’t be sure. Had fuel at schrader valve. Wiggled wires, drove for a bit. died again. No codes active or pending.
Seemed like I could make it die by wiggling wires around ignition switch. Got it home and wasn’t able to make it act up again. I removed some old wiring from a remote start and checked over. All seems good. Maybe ignition switch is bad? Kept cranking a few seconds after releasing key a few times.

TD-5 · Sep 24, 2023

Cranking after the Key is released is normal, Some call it TIP start, Tip the key momentarily to the start position and the start sequence is initiated, the engine will crank for a predetermined period or until the engine starts.

Key Start - you probably already know this.... - Ford Truck Enthusiasts Forums

2017+ Super Duty - Key Start - you probably already know this.... - For those of us with remote start but NO keyless go, when you use the key to start vehicle, you only have to initiate the start sequence, and can immediately release key, No need to wait for vehicle to start, which of course, it...

www.ford-trucks.com

Hazzy · Sep 25, 2023

do you have dpf filter on truck still. just pullin hairs here but could be rear temp sensor on dpf filter causing it to stall on regen.

and how to check if your in regen mode watch this