Hello all! New to this forum, so I'll try to make this short and sweet. I've got an 01 Excursion with the 7.3 that will not start after a rebuild. I've been a diesel mechanic for the past 10 years or so and I'm comfortable diving in to anything. We just finished a full rebuild on the 7.3. All new sensors, HPOP, wiring harness, PCM, IDM, the works. I've got a WTS light, all the fuses are good, I have 185 rpm cranking, ICP shows 2100psi, IPR cranks from %15 to %55. Good batteries, fuel to the bowl, brand new injectors. It will run off of WD-40, and smell a bit of something while cranking, but no fire to it. I've got no codes from the snap on, what else could it be?? Thanks in advance!

 

A bunch of air? Did you try to fill the rails with oil? How much have you cranked it?

 

ICP pressure should confirm rail pressure, right?
HPOP priming takes alot of cranking.

without looking it up 185 rpm seems really low to me. You've got it running on WD and it didn't catch so that shouldn't be an issue.

There are plenty of no start threads and tutorials on here....

 

Yes, and we’ve been cranking on it for several days trying to find the issue, so it should be plenty primed. Yes, 185 ish is a bit low, even though we’ve got it on a charger and it’s cranking like crazy, but it still should only NEED 100+ to fire. It’s got an oem cps in it. I’ve been through almost every thread on here and tried everything anyone has posted and nothing has worked. The only symptom I’m getting right now is that the fuel pw is stuck at 0ms all the time, so that should mean the injectors aren’t firing, but like I said it’s a new pcm and idm and it passes the buzz test with new injectors. I’m just running out of options!

 

you didn't mention the 0ms PW...

 

0ms PW means the PCM and IDM aren't talking to each other. You may have another issue as well, but that one is for certain a no-start.

 

I apologize for leaving that detail out. So, I’ve got power to pin 55 and 71 on the PCM, which is brand new. The IDM is also brand new, where can I test for communication between those two?

 

What scan tool are you using? No communication should have a code or three set.

 

It’s a snap on modis, and that’s what I was thinking too, but there isn’t a single code showing no matter what test I run.

 

Can you run a buzz test?

Sounds extremely similar to my issue that I had a few months ago.

And please don't use WD40 to run it.

 

Yes, buzz test runs fine. And yes, I know WD-40 isn’t great, it was just enough to use as a cheater test for compression

 

Not familiar with that one. And of course, I can't recall the protocol you need to be able to read at the moment.

Do you have a Check Engine light illuminated? If it does a buzz test, there is obviously power to the OBD port and the PCM is taking commands from it so that's a plus. I would think that also indicates communication between the PCM and IDM, but honestly I'm unsure.

 

Yes, those were my thoughts too. It doesn’t have a CEL currently, but if I unplug a sensor to “make” it have one, it will come on. Correct me if I’m wrong, but that tells me the PCM is functioning and communicating to the IDM. If it’s a mechanical problem, my only guess would be the air hasn’t fully been bled out of the fuel lines, but it’s been three days of cranking, so I would have figured it would be bled by now. Unless somehow in the rebuild debris ended up in the head or line? But wouldn’t that just make it run rough? My other thought is maybe the fuel regulator is bad and it’s bypassing ALL of the fuel. If it’s electrical, I’m not sure what could be left, because everything is new, but the 0 fuel pw is weird...

 

I believe a zero pw can be caused by a bad CPS, but you said you are getting RPM - so I guess that is out. Re-check the 42-pin connector? Re-seat both the PCM and IDM? were all grounds re-installed when the harnesses were replaced? PCM ground clip still there (though I think that would show up in other symptoms as well...)

When you create a CEL, does the scanner pull the stored code?

I would agree that if you can create a CEL, at least the PCM is functioning... not sure if we can assume the IDM. But then there's the buzz test that seems to resolve any question there.

 

The engine harness is brand new, and I don't believe it has any grounds its self besides the ground for the IAH. As far as the IDM and PCM, I took both out and checked for power, I'm not sure about grounds. Short story is this Excursion sat for 5 years before it was given to me and it was pooched for parts, so I'm not sure if they're all there, but if they weren't shouldn't I get no response from the PCM? The grounding tab for the PCM is there, definitely made sure of that one. I did use a TINY amount of dielectric grease on the connectors, a small amount shouldn't matter, correct? It will pull a stored code when I remove a wire, but then it will go inactive again when I plug it back in. It has a code for the PATS system stored, but its my understanding that it will go away after 3 driving cycles. I can go into the PATS system and watch it arm and disarm the system when I turn the key, so that shouldn't be causing any issues.