2006 E-450 Short Bus Hard/No start when hot

Aaron_Johnson · December 29, 2007

I am about to take the exhaust hose home over this one!!! Concern only happens when unit is very hot. ICP reading .4-.6v while cranking. All other Hard/No start PID readings within spec. ICP KOEO voltage .21v. IPR duty cycle goes to 85%. ICP sensor has been disconneted and it still acts up.Unit has had IPR,ICP sensor,high pressure pump,standpipes and dummy plugs replaced for this concern. Oil cooler has also been replaced based on ECT/EOT PIDS. I have "extended air checked" the unit by removing the valve covers, and high pressure pump. I made a fitting that bolts to the branch tubes and left the air on it for a couple hours. Air leaks develop on both sides under the rails. after about 45 mins, the branch tubes look fine. Is this considered normal? Rails have been removed all injectors and both rails inspected with no obvious problems.

Base engine oil pressure has been checked, there is no base oil pressure while cranking(using manual guage) but there is flow when filter is removed. I have "load tested" IPR and ICP wiring as well as used a jumper harness and supplied battery voltage to IPR, unit still will not start. What am I missing here? Should I be chasing the low base oil pressure issue even if there is flow? I am thinking my next move should be swapping out all 8 injectors and both oil rails with known good ones. Any ideas?

Bruce Amacker · December 29, 2007

"Air leaks develop on both sides under the rails. after about 45 mins, the branch tubes look fine. Is this considered normal? Rails have been removed all injectors and both rails inspected with no obvious problems."

On a cold start, record IPR command and watch it as the engine heats up. It's not so much what it is as where it goes. It should drift down slowly as the engine warms up, and not increase. Final IPR after warming up is usually in the low to mid 20's, and the diag sheet says under 30%, IIRC. If it increases, you probably have a HP leak. (which is what I think you have). Do you have the isolation tools for the banks? I know this is a last resort on an E-Van. How about a nitrogen test? I think you might have injector inlet D-rings leaking and a nitrogen test will show them up quicker than shop air. Re-read this thread with a similar problem, I did the nitrogen test here.

http://www.forddoctorsdts.com/forums/ubbthreads.php?ubb=showflat&Number=8266&page=5#Post8266

If I was at my wits end and wanted to break something, I'd short the IPR to ground idling, which forces the ICP to 4000+PSI. If something is going to break, it will do it then. Here's what happened when I did it:

http://www.forddoctorsdts.com/forums/ubbthreads.php?ubb=showflat&Number=7040&page=5&fpart=2

Good Luck!

snw blue by you · December 29, 2007

One thing I remember from working with a Navistar engineer was that "If the oil gauge swings, you have base pressure, and oil is supplied to the HPOP"

No need to check for flow.

However if the needle does not move it is indicative of a low pressure pump failure or a massive high pressure leak.

You have already determined the low pump works, move on to the high side.

In my experience, hot or cold I have found that if the injector has failed ICP is very low, below 100 psi, and if it was an STC/HPOP related leak the ICP is usually in the 300 to 600 psi range.

I only use this as a guide to prelim diag, gives me an idea where I am headed and is based on nothing more than what I have seen in 4 years of 6.0s, but its been fairly accurate

LARRY BRUDZYNSKI · December 29, 2007

Quote:

If I was at my wits end and wanted to break something, I'd short the IPR to ground idling, which forces the ICP to 4000+PSI. If something is going to break, it will do it then. Here's what happened when I did it:

Bruce I think speak for quite a few of us how cool your job is... To be able to just break shit just to see what it does!! /forums/images/%%GRAEMLIN_URL%%/rockon.gif Man oh man what a dream job...

slim · December 30, 2007

I had a 2005 E-series ambulance a couple of weeks ago that almost beat me to death. It came in for a crank no start hot and came directly from another dealer. It would only build 350-400 psi cranking and only when EOT was over 185. The hotter it got the lower the ICP pressure would go. After starting cold the IPR duty cycle would lower to around low to mid 20's and not increase with heat. During the air check I had a couple of leaks from around injectors but they didn't seem bad enough to keep ICP so low. I ended up taking the porta-power pump for testing the IPR valve on 7.3L's and adapting it to fit the fitting on top of the HPOP. It would build pressure to over 2k psi while testing but took several minutes to get any pressure but once over a couple hundred psi it went to 2k fast and even held pressure somewhat with leakdown taking about 1 minute. I could see oil coming from the tops of all the injectors while doing this. I had already had the oil rails off and inspected every thing and a couple of the nozzles on one of the oil rails seemed loose so I got a new oil rail and put that on one side. Retest everything and it was exactly the same. I was out of ideas so I put 4 injectors in one side and retested. Now no oil and no air leaks on that side, then I put the 4 injectors in the other side and retested and everything was great. On a hot restart after the injectors were replaced the ICP pressure went over 500 before FICM sync went to yes which was less than a couple of seconds. I learned several things from this truck. First-E-series suck because it takes so long to get the valve covers off. Second, oil rails don't leak, no matter how loose the nozzles appear to be. Another thing of note is with 4 new injectors the oil rail was difficult to install where before it almost fell into the injectors. I think I could have replaced just a couple of injectors and that would have sealed the system enough to generate pressure to start but the best repair was to replace all the injectors. Hope that provides some insight into your problem and everybody learns something.

Keith Browning · December 30, 2007

Every story, every experience and every post we make here has some value and has the potential to add to the discussion!

/forums/images/%%GRAEMLIN_URL%%/thumbup.gif

Aaron_Johnson · January 6, 2008

Thanks for all the replies. I ended up taking apart the drivers side as it was leaking the most on the extended air check. I tried fitting the injectors on the rails with them off the engine. 3 of them fit very loose, the 4th was replaced a short time ago. The new injectors fit way tighter. Replaced the 3 injectors and it is fine now.