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Discussion Starter · #1 · (Edited)
— I typed this out and accidentally deleted it all so I typed it again but not as thoroughly.

So I bought this 1995 7.3 not running and I have multiple 7.3 siting around and I figured perfect no matter what the problem is I can swap that part out. Or the entire engine. It has 162,000 miles.


Sorry for the long read I just wanted to try to cover what I’ve done. I am 17 and love learning this information so any extra information is extremely appreciated. This is not my first time diving into these motors. Do not be fooled by my age. But there is definitely something smaller or possibly huge that I am missing??!

Well I started by plugging the scanner in and doing a buzz test all was good. No codes or anything. I then tested fuel pressure and it was great. Got the scanner plugged back in read the live data and had 40 to 60 psi of oil pressure and the IPR went to 50% instantly while cranking and when the key is off it is just about 15%. I then unplugged and plugged in the exhaust back pressure stuff and put constant voltage to the IPR then replaced the IPR and ICP. Still no dice same low pressures. I then figured I’d throw my injectors in that I wanted to throw in anyway just in case one or more was sticking. These injectors I just had in my other truck. I know they work. I just pulled them out and they have a set of new O-rings on them. After putting them in and after a little bit of cranking it started but about 30 seconds later died and had the same low pressure could not get it to fire again. I did some more Fiddling with the IPR and checking the oil reservoir which was always full.

At this point I’ve tried three IPR‘s and two ICPs. And ohmed each IPR all tested good they where between 10.6-10.2. I then pulled the HPOP Lines off the heads and cranked it and watched the oil pour out. I did the same to my running daily driver 7.3. More seemed To flow out on the running truck so I figured Put one of my spare HPOP’s quick but maybe I was just being a little hopeful and thought I seen less oil flowing out of the non-running truck. Same results occurred. I got that low 40 to 80psi reading from the ICP sometimes I get it to spike to roughly 100. Now today after letting it sit for a week. I cranked a little bit and seen the oil reservoir was empty. I filled it up and it fired up idled for about 20 seconds and died. The oil reservoir now is staying full to the brim. I pulled the plug out of the top of the oil reservoir and cranked and a good steady flow poured out. So is the low pressure system working correctly? I then checked for a possible leak in pickup tube by overfilling it and lifting the rear end. But no change. Is it possible both HPOP’s I have tryed are bad from what I’ve seen they don’t go out in these numbers. Both of them possibly failed in the same way not pumping enough oil seems like HPOP is likely not my problem? But I definitely could be wrong. Throughout this whole process I was checking the oil in the reservoir regularly and was full every time but that once. The first time it started I did not have the scanner hooked up but the second time I did and it instantly when I hit the key it Built pressure and started no hesitation. I’m lost all the easy dummy tests and these quick replacements of parts and no change I’m in need of some help!
 

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I filled it up and it fired up ran for about 20 seconds and died. The oil reservoir now still full to the brim. Jumped the IPR fiddled with stuff again still same results. I do want to get an accurate pressure reading by deadheading the Hpop but I do not have a gauge that goes up that high and proper fittings.
It seems that the truck finally built pressure. What was the ICP reading at this point? With everything you have done you may have air in the high pressure oil rail. It would also be worth while checking the IPR wiring from the connector back to the PCM for shorts to ground/power or open circuits.

Cj
 

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Discussion Starter · #3 ·
Sorry for being confusing after I typed it once I got lazy and just tryed to type the same thing but could not remember stuff in a orderly fashion.

It seems that the truck finally built pressure. What was the ICP reading at this point?
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Yeah it made the proper pressure right away like there was no problem it made just over 500psi to start and idle for 20-30sec. It then lost it all like a switch turned off. It did this 2 times during all my madness of swapping parts and trying different things. Just completely random occurrence’s. I made a little connecter out of a old injector pigtail to put constant voltage to the IPR. If put constant 12v to the IPR it will build about 100psi with slight fluctuation. It was not getting a constant 12v from me when it started the IPR was plugged in normally.
 

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On a normal truck, you will not see a constant 12V at the IPR when cranking or running, since it is a "pulsed" voltage (hence the term duty cycle and a percentage value). If you're swapping parts around, make sure that the IPR is the same type as what should have been on the 95 (edge-filter type). Make sure the HPOP and gasket are correct for the 95. What happens if you crank it with the ICP unplugged? Cheers!
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Discussion Starter · #5 · (Edited)
I did not even realize there was a difference. At the moment it has a 95 gasket on a 96 pump with the 96 IPR. No smoke with ICP unplugged. I think I’m going to put everything back to what was in there originally and start over with a better approach on this issue. I’m not going to put the original injectors back in that will be the only thing different. I will get a gauge and start by deadheading the hpop to test it.

Thanks
 

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1996 Ford F-250XLT SCLB ‘99 to ‘04 F-350 Super-Duty Axles
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Did you happen to check the fuel bowl? Check filter and screen. The 7.3 is does not like aftermarket filters.
 
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