2001 Excursion won't start!
Laughing Gas
Joined: Jul 2018
Posts: 816
Likes: 7
From: Prescott, AZ
Dielectric grease allegedly shouldn't be used on data connections, but I've seen people slather it on Toyota PCMs in the past with no negative effect. I can't say that isn't the issue, but it would be low on my list of suspects.
You mentioned it's "cranking like crazy", does it sound like it is matching the indicated 185RPM more or less?
It sounds like your scanner will in fact read relevant 7.3l codes, so the absence of them indicates a mechanical problem... but how to explain the 0ms pulse width?
On your scanner, are you able to select PIDs to live monitor, as in graphing them? You could watch the battery voltage, PCM voltage, reference voltage, IDM, ICP, RPM, and PW to see what their relationship is from KOEO through cranking. Ordinarily I'd be suspicious of the voltage while cranking, but you've said you're confident that the batteries are good.
Might disconnect the fuel bowl heater because electron fairies. Officially grabbing at straws now. Someone smarter than me should be along shortly...
You mentioned it's "cranking like crazy", does it sound like it is matching the indicated 185RPM more or less?
It sounds like your scanner will in fact read relevant 7.3l codes, so the absence of them indicates a mechanical problem... but how to explain the 0ms pulse width?
On your scanner, are you able to select PIDs to live monitor, as in graphing them? You could watch the battery voltage, PCM voltage, reference voltage, IDM, ICP, RPM, and PW to see what their relationship is from KOEO through cranking. Ordinarily I'd be suspicious of the voltage while cranking, but you've said you're confident that the batteries are good.
Might disconnect the fuel bowl heater because electron fairies. Officially grabbing at straws now. Someone smarter than me should be along shortly...
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New User
Joined: Mar 2019
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Yeah, I mean, 185 is 3 times a second, that’s pretty fast in my book, should it be more?
I totally agree, that’s why the 0ms pulse width is so weird.
Yes, I ran a graph and I’m getting 185rpm, 2100psi, but 0ms. Hooked up to a charger with new batteries so it doesn’t really get below 12V.
Tried the fuel bowl heater, and it didn’t work, but I also had a WTS light so I figured the fuse was good. Speaking of that, both fuse covers were missing, and I can’t find a definitive picture online. However, the 4-5 fuses ABOVE the relays are not getting any power in the engine bay. I think one might be the mystical “fuse 22” but I can’t tell without the cover, and again the PCM is working?
Thanks for all your help, even if you just help me run through things I’ve already tried it’s helpful, just tired of pulling my hair out staring at the thing...
I totally agree, that’s why the 0ms pulse width is so weird.
Yes, I ran a graph and I’m getting 185rpm, 2100psi, but 0ms. Hooked up to a charger with new batteries so it doesn’t really get below 12V.
Tried the fuel bowl heater, and it didn’t work, but I also had a WTS light so I figured the fuse was good. Speaking of that, both fuse covers were missing, and I can’t find a definitive picture online. However, the 4-5 fuses ABOVE the relays are not getting any power in the engine bay. I think one might be the mystical “fuse 22” but I can’t tell without the cover, and again the PCM is working?
Thanks for all your help, even if you just help me run through things I’ve already tried it’s helpful, just tired of pulling my hair out staring at the thing...
Laughing Gas
Joined: Jul 2018
Posts: 816
Likes: 7
From: Prescott, AZ
The electrical on your '01 is a little different than the '02 that I'm more familiar with - almost all of the fuses and relays are under the dash from '02 onward... so I'm not sure what your engine bay fuses do. Is there a dedicated IDM fuse? Then again, you had a successful buzz test.
I'll have to roll mine over tomorrow with ForScan hooked up, but I would think 185 should be more than enough for it to light given decent ambient temps or even halfway acceptable glow plug operation.
I remembered you had a WTS light after I posted the fuel bowl heater issue, no WTS light is the symptom and you're correct you should be good if you have it.
You don't by chance have access to another IDM? I can't believe the air isn't worked out of the fuel rails by now, and the 0ms has got to be either the cause or a symptom.
I'll have to roll mine over tomorrow with ForScan hooked up, but I would think 185 should be more than enough for it to light given decent ambient temps or even halfway acceptable glow plug operation.
I remembered you had a WTS light after I posted the fuel bowl heater issue, no WTS light is the symptom and you're correct you should be good if you have it.
You don't by chance have access to another IDM? I can't believe the air isn't worked out of the fuel rails by now, and the 0ms has got to be either the cause or a symptom.
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New User
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Yes, there is an idm relay, brand new and functioning.
Thats my thought too, and it should only “require” 100+ to start, correct? We’re in TX so the temp was 70 and glow plugs, controller, and harness are all brand new.
It had the old IDM in it, and it passed a buzz test with it but wouldn’t start. I figured it was the only thing left that wasn’t new so I got a brand now one for it and again, good buzz test but no start.
Agreed, but hypothetically, would having air in the lines also show no fuel pw?
Thats my thought too, and it should only “require” 100+ to start, correct? We’re in TX so the temp was 70 and glow plugs, controller, and harness are all brand new.
It had the old IDM in it, and it passed a buzz test with it but wouldn’t start. I figured it was the only thing left that wasn’t new so I got a brand now one for it and again, good buzz test but no start.
Agreed, but hypothetically, would having air in the lines also show no fuel pw?
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OK, so I ran it today for about 10 seconds on lubricated diesel starting fluid. ICP pressure was good, RPM jumped to 800ish, HPOP duty cycle was good at about 15%. However, fuel PW is still 0ms. Correct me if I'm wrong, but again that makes me think that either I don't have any fuel pressure (which I'm about to test) or the injectors are simply not being told to fire. Is there anything in the PCM system that would allow the engine to crank but not fire? I thought PATS and PRNDL switch would keep it from cranking period?
Post Fiend
Joined: Mar 2002
Posts: 19,402
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From: Bonita Springs FL
PATS won't stop it from cranking. With a PATS problem it would crank and run for a few seconds and then quit.
The buzz test indicates that the IDM can talk to the injectors, so your problem isn't a bad IDM or wiring issues between the IDM and the injectors.
I wish I could help you more.
The buzz test indicates that the IDM can talk to the injectors, so your problem isn't a bad IDM or wiring issues between the IDM and the injectors.
I wish I could help you more.
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OK, that's what I thought, and I can watch the PATS system disable and enable when I turn the key on and off, so that should be fine. No problem, any bit of help is good at this point.
I tested the fuel pressure at the bowl, 55 psi. Took apart all the connectors again and cleaned them, still no start. It's got to be something electrical at this point, correct?
I tested the fuel pressure at the bowl, 55 psi. Took apart all the connectors again and cleaned them, still no start. It's got to be something electrical at this point, correct?
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From: Lake Hartwell, GA
I cannot offer any advice, but am following along in your journey as this one is a problem I have not read about before.
EDIT: Was the FP reading before or after the filter? Have you checked the standpipe valve to make sure it is lined up?
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Haha, no problem, I just hope no one has this issue ever again... Its been almost a week of diag and I have no idea what's left. Yes, I know the fuel pump has a timer, but if I leave the key on, it will run continuously...
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The fuel pressure reading was at the fuel filter housing, one of the hex plugs on the back of the filter housing, drivers side. I'm not sure what you mean by the stand pipe valve, I thought that was just on a 6.0? The fuel lines from this go straight to the head which has a built in rail, same with the oil lines/rails.
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From: Lake Hartwell, GA
The fuel pressure reading was at the fuel filter housing, one of the hex plugs on the back of the filter housing, drivers side. I'm not sure what you mean by the stand pipe valve, I thought that was just on a 6.0? The fuel lines from this go straight to the head which has a built in rail, same with the oil lines/rails.
Go to this link and you can see the notch at the top of the pipe.
1999-2003 Fuel Canister Check Valve Stand Pipe with Spring
As for before and after the filter fuel pressure reading, the higher port more toward the driver side is pre filter, the lower port more toward the passenger side is post filter.
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OK, I checked the fuel lines and everything looked good. So, I decided the throw in the broken, water logged PCM that had been sitting for the past 5 years.....and it fired right up 
So, it turns out that my brand new, $1500 PCM with a lifetime warranty did everything it was supposed to, except fire up the motor. I cannot tell you how frustrated I am, but it just goes to show that you should never EVER assume something brand new is %100 foolproof. Thanks everyone for the help, it was such a joy to drive it today!!
So, it turns out that my brand new, $1500 PCM with a lifetime warranty did everything it was supposed to, except fire up the motor. I cannot tell you how frustrated I am, but it just goes to show that you should never EVER assume something brand new is %100 foolproof. Thanks everyone for the help, it was such a joy to drive it today!!
FTE Leadership Emeritus
Joined: May 2014
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From: Lake Hartwell, GA
At least you had the old PCM to try it out. Imagine if you didn't have it how long you would be chasing the dragon...