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Strange Issue

4K views 24 replies 11 participants last post by  White95f250 
#1 ·
'95 F250, stock with the exception of edge evo and DIY Tymar.
Now, here's the kicker. Always starts, idles perfect, drives great. BUT, over the holidays, I put ~1000 miles on it, and in doing so, discovered that it will randomly shut off. Every time it has happened thus far, I was going 75-80 mph, truck acted as if fuel-starved, shuttered, then died. Pull off the side of the road, crank for approx. 15-30 secs, truck starts and is able to continue under its own power. No CELs, no leaks, no power loss after restart, no nothing. I don't have a clue. Suggestions? Also, all filters new, as well as fresh Delo 400.
 
#5 ·
You need to check the fuel pressure (and see if it's dropping off significantly) under load. Get a liquid-filled 0-100 psi guage and hose long enough to connect to the schraeder valve on the Fuel Pressure Regulator and route it so you can get the gauge to where you can tape it to the windshield. I had exactly the same symptoms on my 94 (which turned out to be the high pressure side of the fuel pump ... its two-stage). Cheers!
 
#6 ·
I understand that it may be a fuel pressure problem, but if that were the case, wouldn't it stall every time it gets to WOT? As stated, the last time it happened, I had gone ~100 miles at 75-80, then out of no where, it stalled. I can't reproduce the symptom at will, and it's very random. I've been driving it in town for two weeks without issue, and it's only ever done it at freeway speeds after at least half an hour. Also, if the fuel pump is the problem, how would I know? It's a mechanical pump, so if the engine stalls for any reason, you'd lose fuel pressure. Truck's only got 205k miles on it.
 
#15 ·
Ok, so here's the latest. Installed a fuel pressure gauge and found my fp was ~50-55 psi at idle, ~60-65 at 2300 RPM. Shimmed the FPR to see what that would do, fp went to ~60-65 at idle, 75-80 at 2300 RPM. More better, but still doesn't solve the problem. Drove approx. 50 miles at 75-80 to see if I could maybe coax the gremlin out of hiding. No dice. Problem occurs with both tanks, tanks change without issue. Also, CPS is about 6 months old. Thoughts?
 
#17 ·
A bad CPS would throw a CEL. It could be as easy as a full water separater. Or when your fuel pump gets hot (long period at high way speed) it could be bypassing fuel internally send to much back to the tank instead of to the motor. If you hook up a fuel pressure guage and drive it at high way speed and see if the pressure starts to jump around. If it does you may need to replace or rebuild your fuel pump, and with the pump it would be a good idea to replace to pressure regulator as well.
 
#18 ·
A bad CPS would throw a CEL. It could be as easy as a full water separater. Or when your fuel pump gets hot (long period at high way speed) it could be bypassing fuel internally send to much back to the tank instead of to the motor. If you hook up a fuel pressure guage and drive it at high way speed and see if the pressure starts to jump around. If it does you may need to replace or rebuild your fuel pump, and with the pump it would be a good idea to replace to pressure regulator as well.
As stated, no CELs, stable pressure at all speeds, new fuel filter. No scan tool, but that's what today is for. Stay tuned.
 
#23 ·
Just a thought....whats the inside of the ICP plug look like?

Mine was doing something similar, would run rough shutter and die, but crank and restart till next episode, my ICP was shot (had already changed out CPS). Oil in the plug is an indication of it being junk.

Also a friend had a similar issue also, but his was not so lucky of a problem, his PCM was junk, but ran as yours does...
 
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