2001 7.3L Wont restart when Hot
 

Long time lurker first time poster. I have a 2001 F250 7.3L 89K miles. It has recently failed to restart hot on 3 or 4 different occasions. After it sits for a while it will restart and run perfectly. I have been troubleshooting this and all things point to the IPR. I have ordered one and it will be here in a couple days. My question is, if the IPR is bad, the coil specifically, why does it run perfect once it restarts. Is it not dependent on the coil or IPR while running? Is there any other component that will cause a no start when hot? I have checked all the preliminary items. Oil level, HPOP oil level, battery voltages. The IPR that I removed seemed clean and working. However the coil was reading more OHMS than the 10-10.6 that I see it should read. Also while heating it up, the resistance seemed to increase. Also what is the most economical scanner that I can buy that will work on this truck. I have an Android version and it only shows very limited data. Thanks in advance.

IPR gets hot and needs to cool. Pour cold water or ice on it when it won't restart. Should start then.

if resistance is going up when hot, it might just be the coil only going bad

Yes the IPR is out. I am hoping that it is the only issue. But while I have it down waiting on the new one, I was trying to eliminate any other things that could cause the no start when hot. After the truck restarts, it never misses a beat. Drove more than 90 miles home after the first failure without a hiccup. I have read some people say they have had loss of power etc while driving. I have had none of those issues. This truck is mostly used for 2 hour trips to the lake and want to try to make sure it is fixed before I head out again.

Failing starter can be too weak to start when they get heat soaked. Many auto stores will do free testing, if you hand the starter to them. And the CPS is a common issue for bad running/no start.

What ohms did you see on the IPR solenoid?

Torque Pro and ForScan are favorite code reader/sensor scanner apps. They have things specific for 7.3, not all apps have that. Assuming you already have the Bluetooth OBDII dongle you're good to go.

I have changed the CPS out three times during the failures. Have the Old style black one installed currently. The Engine spins over quickly during the failure. The only thing that I can do to make it spin over as fast and sound the same is unplug the main square harness at the Drivers side valve cover. It measures 12-13 ohms cold and can make it read higher when it is heated. I will check out those scanners.

UPDATE..Well I installed the new IPR. After I got all the air out of the system, the truck ran perfect. Drove a few miles let it Idle for a bit. Shut it off. No restart hot. Then this morning, no start cold. I seem to be heading the wrong direction. As I have read, if the ICP is bad, won't unplugging it allow it to start in a default mode? Does it sound like maybe the IDM is bad? How can I test it? Any other ideas? Frustrated. Thanks.

You are correct, you can unplug the ICP as a test and it will default to the value required to start and run. This is the best way to identify if the ICP is going bad other than seeing oil in the electrical connector.

You could also remove the high pressure oil connections to the heads and pressure test the heads with shop air. If you have a leaking injector o-ring, hot oil (which is much thinner) will leak past the o-ring, reducing your hpop pressure during a hot start attempt. The leak may not be bad enough to noticeably affect engine once it is running.

Have you checked your fuel filter for a black discoloration? Leaking high pressure oil will migrate to the fuel filter.

Larry

I hooked up pressure gauges last night and confirmed 56Lbs of fuel pressure and 2300LBs of oil pressure during the start attempt. I checked the fuel filter again last night and seems good. I am hoping it is the IDM which I have ordered for tomorrow. I have no other ideas to try at this point. If anyone has any other theories I would appreciate hearing them. Thanks.

Update-The truck is now running. After installing a repaired IDM still no start. Started back at square one fuses etc. Found the relay for the IDM had now failed. Originally it was a no start hot, then no start at all. Got the truck running, however it runs a little different than before. Re-installed my original IDM and still runs a little different. Can the IPR change the way it runs at low to mid throttle? May put the original IPR back in.
Thanks for all the help.

Do you think that it might be time to use some more sophisticated troubleshooting methods as mentioned in this post? Even if a good scanning app doesn't help you this time, this will not be the last time you have to work on your Ford. The engineers have schemed up several different ways to make it act up!
Larry

NEVER ever ever do this. Why does this keep having to be said over and over again? Never poor cold water on any hot engine components....good grief. :-X19