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Discussion Starter · #1 ·
I recently rebuild the 7.3l engine in my 2K F350, the motor had a blown head gasket and is the only reason i chose to rebuild it. When i go to start it it has an extremely long crank time (close to a min) before it starts but when it does start it seems to run great. When the motor gets up to regular temps and is put into gear the truck goes maybe two inches and dies.. impossible to restart! Not my first 7.3L and its not the first one I've had apart but its defiantly got me stumped on this one. I'm currently leaning towards the High Pressure system, but don't want to go down that path quite yet.. Thanks in Advance for the help.


-Titus
 

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Try pouring cold water on your IPR solenoid and see if it won't restart right away. Pretty common issue causing a no start on a hot motor. The other issue - break out your ohm meter and check from the IDM to the UVCH plug. Also ohm out the injectors from the outside harness. That will give you an idea if the issue is inside the valve cover or in the wiring between the IDM and the plug.
 

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Discussion Starter · #4 ·
Thanks! How do i OHM from the idm to the UVCH, and what should they be? For the injectors i understand how to ohm those but what should i be looking for resistance wise? Is the idm underneath the driver fender?
 

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Yes, the IDM is behind the F350 emblem on the driver's side. You get at it by removing the fender liner (or at least the rear part of the liner.)
 

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This is an instructional on how to do the test. You would expect no resistance between the IDM pin and the corresponding UVHC pin, but you could start with the test as described and then break it down to test at any pins that give you a bad reading.
 

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Discussion Starter · #7 ·
Great, thanks guys. I found the idm and took it off last night and swapped another idm to run the BUZZ test and got different results. I’ll ohm out the harness when I get home. Thanks for the info in that, very helpful. What does “high to low side open, bank 1” mean? I know bank 1 in passenger but I’m not sure what high to low means

-Titus
 

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Discussion Starter · #8 ·
Ohm'd the harness at the IDM port 5 out of 8 registered as 2.7 and the other 3 registered as 2.6..Obviosly not in the ranges you provided but what does it mean if its under speck?
 

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Discussion Starter · #9 ·
I did an ohm test in my glow plugs with a spare pigtail I had for the uvch the passenger side came up as 7-14 ohms. Would that cause the motor to stop when it got hot or is that still a high pressure oil issue? I scanned for codes and nothing is showing..on the original IDM cylinders 1,3,6,8 all show up as high to low side open and bank one high to low side open. When I put the IDM out of a running truck into mine the buzz test only resulted in bank 1 high to low side open. So I put my IDM in the running truck and it cranked up fine..
 

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Glow plugs won't shut it down when hot. Bad GPs will make it start hard when cold. Using that tech bulletin (post 6) you should be able to check for shorts in the harness. Did you pour cold water on the IPR solenoid when the truck is hot and dies to see if it starts (post 3)?
 

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Discussion Starter · #11 ·
No I haven’t done that yet, I can’t hardly get it started. It takes about a minute of cranking (off and on) to get it started. Maybe a little longer..post #6 in this thread? I already did those three tests on my IDM harness and came out with 2.7ohm on everything
 

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No I haven’t done that yet, I can’t hardly get it started. It takes about a minute of cranking (off and on) to get it started. Maybe a little longer..post #6 in this thread? I already did those three tests on my IDM harness and came out with 2.7ohm on everything
There are also some tests on there that you should get infinite on. If you get something then you have a short. Are you saying now that it won't start cold?
 

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Discussion Starter · #13 ·
The tests that where supposed to come beck infinite Came back good. But yes, i cant get it started cold now either. When it started before it was like it had to build up speed on the motor before it started and then started. i look a video of the exhaust when cranking and some white smoke came out before it fired up the last time it started. i tried to test the glow plugs and the drivers side cam up as 1.3-2 ohms and the passenger as 7-14 ohms. passenger side is the side that threw the bank one high to low side code as well.. Found out that the truck had overheated before i rebuilt it and also that the head lights don't work and they did before the rebuild. Could this be a PCM issue? (Oil pressure doesn't build up right away either but i figure that normal since my other 2 7.3Ls do the same.)
 

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Discussion Starter · #14 · (Edited)
ICP reads Well over 2K when cranking, could this be an Injector issue? the injectors got new ORINGS when i reassembled the engine. Again thanks for all the help. I appreciate it and want to learn as much about my own truck as i can!
 

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i tried to test the glow plugs and the drivers side cam up as 1.3-2 ohms and the passenger as 7-14 ohms. passenger side is the side that threw the bank one high to low side code as well.. Found out that the truck had overheated before i rebuilt it and also that the head lights don't work and they did before the rebuild. Could this be a PCM issue?
If you tested the GP's individually, the ones that come up over 2 ohms are going bad. But the GP circuits are separate from the injector circuits and wouldn't cause the injector code. Headlights are not connected to the PCM.
 

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Discussion Starter · #16 ·
Okay, I’ve got new ones of those coming today or tomorrow. What about the dies when hot/won’t restart? Could that be injectors? Could the seals inside have find bad when it overheated?
 

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Discussion Starter · #17 ·
Check engine light hasn’t come on, service engine soon light came on twice but hasn’t come on the past couple times I’ve tried to start it
 

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Last summer I had an issue in which my 02 7.3 would start fine but would not start after shutting it off if it sat for 20 mins. But would restart if it only sat for less than 15 min. Thought it was CPS and changed that but still continued with the same problem. I then suspected the IPR solenoid coil was heat soaking and losing continuity when I shut the engine down for longer that 20 mins. Changed IPR and fixed the issue. I would suspect your IPR.

Generally my truck will start at 50 degrees and above without Glow plugs, but under 50 degrees I need glow plugs to work. Plug in the engine block heater for 2-3 hours. If it still doesn't start then its not a glow plug issue.

If a truck sits overnight or for a few days, and when it attempts to start or starts, and stumbles to catch it's idle for a minute or so, then injector oil orings are leaking draining the oil from around the injectors while it sits. And takes a minute for the HPOP to refill the area around the injectors before it can pressurize the oil. Leaking can be checked by disconnecting the High pressure oil lines from the HPOP. Tie them up vertically and fill them with motor oil. Then let them sit over night and see if the oil goes down.

Almost two years after installing new injector cups the truck ran hot. Pulled thermostat out still ran hot. No water leaks. Removed radiator cap and everything was fine. Changed 2 year old water pump, installed new thermostat, new hoses, and new radiator. Tow days later truck ran boiling hot. Took 6 gallons water to fill out of a 7 gallon system. Then suspected a cracked head and the engine must be burning the water due to no leaks. Removed Thermostat and loosened the radiator cap and drove it for 6 mo. with no problems. Decided to do a rebuilt long block and discovered the bottom seal of injector #8 was leaking into the cylinder. Which must have been a high pressure leak.
 
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