Truck shuts off while driving, then no start.

Ford7.3SD · Sep 17, 2015

Its been a while since I have posted on the forms, but I'm having an issue with my 2001 that is stumping me.

The truck will start/run/drive just fine in the morning. It will run for around a half an hour or so until its nice and warm and then it will just cut out, no stubbles or any warning that the truck is acting up. Then it won't start for around a half hour, after a half hour or so it will fire up and run just fine until it cuts our again.

I found the IPR wires to be disintegrating, so I replaced it with the Ford repair harness. no change.

When it restarts, it acts like its slowly building oil pressure until it fires up.

1) while dead the truck will crank and crank with no build in oil pressure. (I have a gauge plumbed in to the passenger side oil rail)
2) oil pressure at full throttle struggles to go past 2K in my 140 race tune and maxes at 2500 but it only spikes to that PSI.
3) CPS is brand new
4) no codes are thrown when the truck dies

Any help to get me pointed in the right direction would be awesome!

Thank you!!

sideswipe · Sep 18, 2015

When you try to start it does the rpm guage bounce

Arisley · Sep 18, 2015

You need to get a scanner on there, monitor ICP and duty cycle. See where it is when it dies. Sounds like you have some serious HPO issues. Maybe a combination of week pump and bad injector O-rings.

BTW, where did you get your new CPS from. Parts houses are known to be crap, right out of the box. For that matter, been seeing some issues with Ford CPS being junk out of the box. With the age of our trucks, it would not surprise me if Ford got their CPS from the same place NAPA and O'Reilly's do.

Ford7.3SD · Sep 18, 2015

Yes, the RPM gauge bounces when I try and start it.

I will get a scanner on there, and see where the duty cycle is when it dies.

When the truck is dead, cranking it won't build more that 50 PSI while cranking in the HPO system until it decides it wants to fire again.

I got my CPS from O'Reilly's... I probably should try one from ford. This grey one is replacing my old black one.

Northwoods2002 · Sep 18, 2015

Oil in the ICP connector?

Got n extra IPR? Swap the electrical solenoid on and see if it does it. I took a video of my old solenoid, when hot creates an open and truck won't run. Let it cool down a few degrees and it fires right up.

Ford7.3SD · Sep 18, 2015

Yes, there is a bit of oil in the ICP connector

That was my plan today was to swap the IPR. That sounds about like what my truck is up to, let it cool off and it will fire right up and run fine.

Jomax · Sep 18, 2015

I'm betting IPR or you have a internal oil leak.

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dieselmandustin · Sep 18, 2015

This may sound dumb but I have to ask. Does it have oil in it? I found this out the hard way when I was a youngin. Lol truck would fire and run for 15 min or so then die. Would not restart till it sat a while. Then fire back up and run just fine for another 15 or so. I took it to Ford dealer they couldn't figure it out. Hauled it back home and my dad pulled the dipstick and nothing on it. A gallon of oil later problem fixed. Not trying to insult you or anything like that. I just know sometimes the simple things get overlooked sometimes. Hope you get it figured out. Good luck.

03 7.3 · Sep 18, 2015

Similar issue

I had a similar issue, would die/shutoff while driving with no warning, except mine would still fire right back up.

Luckily a dealer in the area has great diesel techs and they diagnosed the issue as a bad ICP in the parking lot in less than 5min with the scanner and had me fixed up in another 5 (they already brought the tools with them).

Pretty fortunate as they also only charged me cost of the part as well.

I know not all dealerships are this great to deal with, but the Only way to diagnose is a good scanner unless you like throwing parts and money at it.

Good luck and I hope you get it figured out.

Arisley · Sep 19, 2015

Without a scanner, all you are doing is guessing.

These motors are not 1968 Big Block Chevy's.

You have two diagnostic methods.

1. Make a WAG and throw parts (and dollars) at it till you fix it.
2. Spend the money on a scanner, diagnose it and fix it.

BTW, you can skip the scanner option if you are really good with wiring diagrams, a multimeter, and knowing what voltages mean what. I actually know a 7.3 mechanic that is that good.

Ford7.3SD · Sep 21, 2015

Thanks for all the help guys!

I ended up swapping IPRs with a known good one, and it turned out to be the IPR. Went down to Ford, picked up a new one and the truck as been great since.

But you are very right Arisley, I need to get a good scanner as I have 2 of these trucks...:doh:

Arisley · Sep 22, 2015

I recommend Auto Enginuity. You buy the program and the enhanced Ford bundle. load it on a laptop with Windows, and you are good to go. It will read basics on any vehicle, it will do everything with Fords. Mine paid for itself real quick between my truck and the wife's Lincoln. I bought a little Dodge Durango, and purchased the enhanced Dodge bundle, and that paid for itself real quick also.