96 7.3 5 spd. Truck ran fine earlier this summer but has set for a few months since then. Last time it was started it would run for a few minutes and die like the key was shut off about a month ago. Went to start it and it will crank no start no smoke. Used to do alot of work on 7.3 but havent done much lately just wanting to verify my test results. I suspect the PCM is the problem. I have auto ingenuity not showing any codes. Passes injector buzz test. Glow plug light comes on and glow plugs work as they should. As far as i can tell everything is functioning as it should. Check engine light will come on after a few seconds of cranking but goes back out as soon as stop cranking. Readings may not be exact didnt write them down. Truck did have a chip on it but was pulled off to send for a reburn. Batterys unhooked while removing. Truck ran fine after chip removal.

1 Battery voltage is good. New batterys and on charger while testing.
2 Crank case and hpop full of oil
3 Tach moves around 250rpm while cranking. ( Also swapped cps same reading).
4 ICP reading of 250 psi for 10 seconds or so then jumps to 2500psi while cranking. Duty cycle low then jumps to 54%.
5 Capped off both hpop lines still no start and same reading as #3.
6 Swapped IPR and ICPs with same results as #3.
7 Manually applied battery voltage to the IPR for a short time and the truck will start and run.
8 Have 12v power on one side of the IPR plug.
9 Checked resistance from the IPR plug to PCM .2 ohms on ground wire.
10 During testing had a mechanical gauge hooked up and hpop was not building pressure until 12v was manually applied.
Has been raining for the last two days and notice floor board is wet. Possibly water has leaked around the windshield and shorted the PCM. Is there anything else I should check before ordering a new PCM?

 

I'm noting that this is not the truck in your signature. Most of the troubleshooting advice we have on this forum for no-start should be the same for the '96 though.

If it runs when you apply 12V to the IPR coil, it sure sounds like wiring to the IPR or related wiring to the PCM, or the PCM itself, especially if the PCM is wet on the inside. I thought the PCM was pretty well protected from water leaks, and it was the GEM that was susceptible to windshield leaks, but not sure now. Would be good to deal with that water leak and see what all has gotten wet under the dash.

Since it's a free test, did you try to start it with the ICP sensor unplugged?

Normally with no smoke, I'd say check your fuel pressure and tank screens, but since it fires up when you apply 12V to the IPR coil, no reason to look at the fuel side.

 

Don't buy another PCM. Send it to Diesel Technologies of Chattanooga. He can test it for you and fix what is wrong, if anything. I believe turnaround isn't to bad if you have a few days to spare.

https://www.dieseltechchatt.com/prod...12361158393919

 

No it is not the one in my sig. I wasn't paying attention to which forum I posted in this is the first obs I've owned always had superdutys. I tried to unplug and I've swapped the ICP with no change. I am going to pull the PCM tonight take it apart and see if any water has gotten in it. From all the testing it has everything it need to start but no ground supplied to IPR. Has anyone tried to load the IPR ground wire while cranking the engine using a test light? Or able to see voltage on a meter using the IPR wire for the ground?

 

I’m no expert by any means but a while back I had a no start issue that I traced back to the wiring feeding the IPR.
After removing the black wire loom, I found the insulation had dried and crumpled which caused the wires to short out.

Worth checking.
Good luck.

 

This is what I found when I removed the tape and loom on the IPR pigtail.

 

https://www.ford-trucks.com/forums/1...-pressure.html