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Discussion Starter · #1 ·
Well, the old gremlins are persistent. I still have a periodic no start. I have replaced the cps
and the tach is moving while it cranks over.
Any ideas out there? I have changed the sensor recently. Is it a given that a moving tach means
the sensor is ok? It sounds like a sensor fail no start. No attempt to fire. I thought it may be the
shifter switch but moving the shifter does not seem to work. So far it has always started after a short wait.
HPOP going out??
 

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Discussion Starter · #2 ·
How does the shifter switch work and will a sloppy shifter cause an intermittent
crank no start?? Any ideas?
 

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The shifter switch will cause a no-crank. It disables the starter if the shifter isn't in Park or Neutral.

I would say NOT the HPOP, but more likely something electrical. Your best bet would be to get it on a Powerstroke capable scan tool and see if there are any codes. You can also monitor parameters when cranking. Voltage at the PCM is important and needs to be above 9V while cranking.

Is it a hot no-start or any time, cold or hot?
 

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Discussion Starter · #4 ·
Thanks good info. I don't remember a completely cold morning no start but in the day after maybe
an hour or so rest it has done it. So definitely warm.
 

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I'm a little confused. Does it not crank, or does it crank but not fire?
 

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Discussion Starter · #6 ·
I'm a little confused. Does it not crank, or does it crank but not fire?
Sorry for not updating. It is a crank/no start problem. I think I narrowed it down to
a bad ICP. Picked up a new oem sensor from Ford-$210! and for over a week now it
has not failed to start. Still have my fingers crossed however.
 

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Discussion Starter · #7 ·
Well, my luck ran out as it failed to start today. Started right up cold and then cranked no start after a ten minute drive to job site. New cps, icp, and ipr is about 3 yrs. old. Going to check some wiring at sensors tomorrow. It always cranks eventually after letting it sit for a short while. Gonna check IPR orings. Also*** when it will not start it sounds and feels strange while cranking. Very rough sounding.
Any ideas on that?
 

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Could be injector o-ring leaks. That would prevent starting when hot as the hotter oil can get thru the leak easier than cold oil so the HP oil pressure can't get to 500 psi and the PCM won't fire the injectors. Oil can either show up in the fuel filter, or it can leak into the valve cover spaces. With a scan tool, monitor ICP, cranking speed, IPR duty cycle, and fuel injector pulse width. Crank speed has to be at least 100 rpm, ICP at least 500 psi, IPR duty cycle from 14-35%, and fuel injector pulse width between 1 and 6 mSec.
 

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Discussion Starter · #9 ·
I'll see if I can get a scan. New reman injectors installed 3weeks ago, and this problem was before and after the new injectors. The injectors were an issue but not related to this CNS. This CNS is intermittent btw. Just went 2 weeks with no problem. Seems to be on warm engine. Thanks K
 

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Discussion Starter · #10 ·
Using forscan rpm obviously good, ICP reads consistently over 500, IPR a low of 13.67,
codes: p011, p111, p0196. Cranked no problem cold today.
 

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None of those codes exist for a 7.3L.

Try doing the cranking parameter test immediately after you get a no-start. It sounds like you were monitoring while it was running. The test has to be done while you're cranking the engine to get valid results.

You can also use fittings to block off one of the HPOP hoses while cranking. If it starts with one blocked off, but not on the other. the one that's connected will be where you'd find injector o-ring leaks. It's possible one of the o-rings got damaged on install, but the fact that it occurred before and after injector install kind of points away from that.
 

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Discussion Starter · #12 · (Edited)
None of those codes exist for a 7.3L.

Try doing the cranking parameter test immediately after you get a no-start. It sounds like you were monitoring while it was running. The test has to be done while you're cranking the engine to get valid results.

You can also use fittings to block off one of the HPOP hoses while cranking. If it starts with one blocked off, but not on the other. the one that's connected will be where you'd find injector o-ring leaks. It's possible one of the o-rings got damaged on install, but the fact that it occurred before and after injector install kind of points away from that.
Ok. what about the IPR operating at 13.67 minimum, but mostly over 14? Edit: now with engine warm, IPR reading of 12.5 but reads over 14 while cranking. This is a crank and start situation.
 

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If your cranking IPR duty cycle runs up to 65% on cranking, then you have an issue. It normally shouldn't go higher than 35% on starting.
 

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Discussion Starter · #14 ·
So 12.5 at idle is ok? I ordered an oring kit for the IPR btw. Next stop HPOP testing and then
mechanic. Thanks for your input K...
 

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Yep, IPR can go to 11 or so at idle, depending on the engine and tune. If it goes way low, that means there's an obstruction in the relief port. There's an edge filter in there that may need service if that's the case.
Here's a good resource for the HPOP system.
 

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codes: p011, p111, p0196.
OBD2 codes consist of a letter & 4 numerals. When you post them, make sure you copy them correctly.
 

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Discussion Starter · #17 · (Edited)
Well I finally was able to use the forescan while the truck was cranking but not starting. IPR shows at 35. Time to take it to a mechanic. It seems to be happening more often as well.
Never on cold start, and it always starts after giving it 15-20 min. Plus I need to get a proper scan.
 

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Discussion Starter · #18 ·
Follow up:
I left the truck at a mechanic for two weeks and he could not get it to reproduce the crank/no start.
So back in my court. I asked him what he would bet on as the cause and he said HPOP. He said the
next time it would not start pour some cold water on the pump and see if it would start. Any thoughts from you gurus? The only other thing I can think of is the idm/pcm. Don't want to throw these expensive parts not really knowing. Thanks,
 

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If it is only acting up when warm then yes, pour cool water down by the IPR on the HPOP if it starts back up then it would point to the IPR not the actual HPOP. Have you checked to make sure that the tin nut on the IPR hasn't backed off or came off ?
 

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Discussion Starter · #20 ·
If it is only acting up when warm then yes, pour cool water down by the IPR on the HPOP if it starts back up then it would point to the IPR not the actual HPOP. Have you checked to make sure that the tin nut on the IPR hasn't backed off or came off ?
Yes. I replaced the IPR a couple years ago with new OEM, and have since replaced the entire
fuel system and so the IPR should be good. I managed to connect forscan once while it would not start and the readings looked good assuming the scan tool is accurate.
 
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