Running rough, no solutions yet...

[Sms888]

'96 7.3 F350 E4OD 4x4 45k.

So she started to run funny like a clogged fuel filter… Hard starts, lots of cranking. Once started, runs ok, less power but she runs. Drive it around the block, starts to die, super low idle.


Not the filter, threw in an extra CPS I had laying around after I found oil in the ICP. New ICP. Nope, started looking around and found burnt UVC connectors. Scanned it, found Inj2/4 open circuits. Started there, ohm'd everything out from the 42 pin up, did gaskets, pigtails, new GPR. All good circuit wise.
Still running rough, IDM was corroded plus water in the connector. New IDM, No luck.
Fuel Pressure seemed ok, as it cranks, each crank bumps it up 20psi, runs at 55psi +-. Maybe a little low, but its a new fuel pump in the spring. Fuel bowl gaskets are all new also.
Scanned again, all numbers check out, ICP, IPR, Cranking, all good. Run several buzz tests, CCT's, self tests, etc.. No codes, nothin.. Decided to remove and clean IPR. Solenoid ohm'd out at 10.2, cleaned(looked pretty good though), orings were good, left them for now.

So, I'm not really sure where to go from here, I have a scanner and a good DMM, but no 7.3 diagnostic tools. I know my IDI in and out, but this electronic stuff… Maybe an oversight, maybe I just haven't gotten to the actual problem yet but I need my truck back!! Next steps?? Thanks all!

 

[79jasper]

Need to watch ipr Duty cycle and icp.


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[Sms888]

That's the thing, they seem to be within spec according to what I dug up. What should they be? At first startup, IPR is around 17% but comes down to 12-14%. ICP starts at around 750, idles down to about 580. When I drive it, they seem to be right where I read they should be. She won't start when its warmed up now, but I'll try to get her around the block again and see what happens. I would post my scan data, but I doesn't like to accept my usb drive...

 

[OLDBULL8]

HPOP.

 

[Sms888]

UPDATE: Just took her for a spin, crank speed was a little slow, just under 150, but it was a little chilly here last night. However, once she fires after about 4-6 sec of cranking, it still sounds a little off. Drive it down the road and it still has low power, and tries to die as I slow to a stop. The ICP hovers around 825PSI and the IPR doesn't drop below 18% unless it's starting to struggle. Sounds like its missing or getting barely enough fuel, but fuel pressure is good at idle… I'll check the batteries in the meantime, but they are fairly new, but that shouldn't affect running, just starting.

 

[Sms888]

HPOP oil level was good, checked it a few times during my toying around. How can I know for sure?

 

[Agnem]

Based on your oil system observations, the problem does sound more like a fuel supply issue. Can you T into your fuel line going to the heads and check the pressure?

 

[Sms888]

No luck, had to side step to another project… Back to this truck, fuel pressure was good at the heads. Tank leakage maybe? Bleed down?

 

[79jasper]

If no fuel/real low pressure, you'll normally hear the injectors make a real loud hammering sound.


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