^^^ That is a great explanation of the startup sequence, thanks. I don't think I've seen it explained like that before.

I don't think rpm is a problem for you either. 150 rpm looks like the speed for my starter, works great. "The sheet" says it should start with the starter spinning as low as 100 rpm. Keep those batteries charged up while you are working on it.

Links to a PDF file of a diagnostic sheet from the factory shop manual.

https://www.thedieselstop.com/faq/94.../9573LDEDG.pdf

 

ALL THINGS considered, Im well ready to start throwing NEW parts at it. Any opinion on the best IRP? Motorcraft or International?

 

https://www.riffraffdiesel.com/ipr-i...gulator-96-03/

 

NEW DATA. Also, resistance across IPR, 10 ohm cold, 12 olm hot at no start. Below 4 pics with notes tell my story.

 

20% coil resistance increase when hot, hmmm not great IMO

I would try some water to cool IPR coil down and see if it starts. If it does then you know what the issue is.

Idle with that much IPR % duty is a sign of leaking injector orings. Should be about 11%

 

Ipr of 50% and 275 psi....ding ding ding...we found the problem.
that resistance change isn't bad. Pull covers and look for that bubbling crude!!

 

Plug the lines to the heads and test again. Do one and then do both. If you see a rise in pressure you can tell something in that head is leaking. JIS #6 fit mine.



If you get a plug that you can screw a gauge into it gives you more ways to test. There is more about this in my thread. There's a link to a DieselTechRon video too.

The diagnostic sheet I linked to in post #61 addresses this.

 

Took a break on the 7.3 to do an injection pump on a 97 Chev 6.5. Way easier that the injection system on this Ford!

Anyway, at this point I see a few options recommended,
1- more diagnostics to isolate pressures
2- hose down the ipr to see if the heat is killing it - maybe it will start when cooled
3- pull the covers and look for oil leaks
4- put a new IPR on it and if it still dosent start when hot then pull the covers.

Wont take much to ice down the IPR. Will try that next.
After that Im thinking of pressurizing each head individually and looking for leaks there. IPR, HPOP, WHATEVER, If I have leaking o-rings they have got to be done anyway.
Rabbit Hole! Rabbit Hole!

What I cant get over it how PERFECT the thing will run all day long, and how good all the pressures look in Forscan - untill I switch it off - at which point it wont restart until dead cold again!,

 

Parts swapping is the real rabbit hole. Once you start you don't know if problems are from something you did or if was always there. Some of these threads have no end and the guy is never heard from again. I guess they just sell the broke-down truck and move on.

It's worth it to fix it. When it runs great now - it will run great like that all of the time.

The numbers for hot idle might show a difference with IPR% - Uh oh - made your list longer.

If you plug the passenger side you can still read the pressure from the ICP. It might start if leaks on the passenger side are causing the No-Start. The plugs are cheap at a hydraulic shop.

I sprung a leak, looks like I might need a water pump. Previous owner said he paid big bucks for a new water pump, 25 year old trucks, anything can go.

 

Here is a video that may help. First half is some troubleshooting techniques and second half is watching a failed injector o-ring symptom with covers off. One of the best videos I've seen in a long time. Quite possibly you have already reviewed this?


Since you seem to be into troubleshooting before throwing parts at it, a very good thing indeed, this might be a good time just to remove one or both valve covers a take a look when cranking. Good luck, I admire your perseverance on resolving this problem.

 

Here's a thread where the guy just dropped off the face of the earth. I hope he's OK.

https://www.ford-trucks.com/forums/1...-too-long.html

 

Well, I became absorbed in the IH truck build, then ZAP!, nothing. i see what you mean.
THANKS SO MUCH for everyones suppprt, some more than others as you have been so dedicated and loyal to my project. Im wanting to throw a Bar b que for you guys already! The positive feedback takes me to a new level of motivation to get this thing done!

PLAN. I think Im going to pressurize each head independently - with oil - where the HPOP lines attach. i will build a gauged air line filled with oil so as to inject no air. once I pressurized the far end of it it and shut the valve I can watch the gauge for bleed down. This will help me locate which side the leak is on.

I love the last video on this - NO I hadnt seen it. but now Im totally motivated to find a split o-ring and dig it out. Hopefully its just one! If there is one. (Rabbit hole??) Using my PLAN above is as simple as I can think to do it.

 

If you find a set of bad O-rings on one injector, the possibility that other injector O-rings aren't far behind is quite high. I would replace all of them on that side at least, as long as the valve cover is off. Just to help you a little farther down the rabbit hole!

 

..........

 

Not helpful Fordman67.
Got no intentions or pupose for 500 psi. Whats your point? O-ring wont leak down with less than 500 psi?
I can throw parts, mindless labor or diagnostics at.
Im working on diagnosing which side is loosing pressure. Maybe one, maybe both, maybe neither.