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I'm about to loose it

3K views 22 replies 7 participants last post by  TwistedPowerstroke 
#1 ·
Hello all!

I'm writing this new thread because I'm totally stumped.

My truck is a 96 7.3 335K miles. 5spd 2wd

I've been reading other threads and changing parts for about 2 months now.

My truck takes about 10 seconds of cranking to start. I get the error that says ICP not detected during crank
Runs OK when cold. When I gets to normal operating temperature, it runs rough, low fuel pressure, no power at low rpms, have to Rev the engine to 1200 rpms for it to move. If I turn it off, it won't even start, I have to let it sit for a while for it to start again.

It has a new HPOP, ICP, IPR, FUEL PUMP(twice), valve cover gaskets and harness, injector o rings, oil rail crossover, oil reservoir is full, glow plugs and relay
When I unplug the ICP still no start.
Buzz test pass
Normal blowby

Here are some numbers
Warm engine
637 RPMS, ICP voltage 0.67, ICP pressure 405 psi, IPR duty 70.6 (why?.)
1100 RPMS, ICP voltage 1.19, ICP pressure 1013 psi, IPR duty 53.1

Cold engine
620 RPMS, ICP voltage 0.64, ICP pressure 405 psi, IPR duty 41
1100 RPMS, ICP voltage 0.94, ICP pressure 810 psi, IPR duty 28

The HPOP, ICP and IPR, are from Pensacola Diesel. Are they good? All the other parts are from dieselorings.com

What now?? :mad:

Thank you!!
 
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#2 ·
IPR duty being that high could be your problem. Low fuel pressure i'd be concerned with too, no reason to loose fuel pressure as its an entirely mechanical system (unless you converter to e-fuel?)

What i did to diagnose a bad IPR on my truck was go to oreilly's and buy one, they call it a "fuel pressure regulator" not an IPR though. If it doesn't fix your problem, pull it back out, clean it, and return it.

Make sure to check wiring on the IPR too, and the entire fuel bowl harness. Check for burnt pins or oil in the connector.
 
#4 ·
Wouldn't be the first time, not sure what else would cause duty cycle to be that high though. My truck at idle, when warm, the duty cycle is about 4-6%, and about 12% while cruising.
 
#7 ·
I also forgot to mention this

During cold crank, ICP pressure stays at 0 for about 8 seconds, IPR duty 70%, then the SEL comes on, ICP pressure jumps to 800-1100 and it starts

During hot crank, ICP pressure 200, IPR 50, then ICP jumps to 405 and it starts.


Thank you.
 
#9 ·
This could very well be an electrical issue. Injector pulse width essentially is on time per degree of camshaft rotation. The HEUI system uses high pressure oil as a hydraulic medium but also use electric pulses... you can check continuity, resistance, and do a voltage drop of the HOT harness and see if the numbers are what they should be

Sent from my SM-G930V using Tapatalk
 
#12 ·
IPR duty cycle is NOT injector pulse width. IPR duty cycle determines injection pressure. Injector pulse width is controlled by the PCM at each injector individually. With the possible exception of an oscilloscope and a highly trained and experienced user, the only way to measure either one is through a real-time data device.
 
#13 ·
With the ICP being 0 for the first 8-9 seconds, then all of a sudden jumps to 800-1100 psi and setting a code, it makes me think the ICP is faulty and once the code is thrown, the computer sets a default ICP value and makes the truck start.

Not sure on that though, can anyone else chime in with my theory?
 
#18 ·
Rig up a setup to dead head the pump to a gauge. That will show if you have a pump issue.

Something is not right. Remove the valve covers and start it up and watch the spill ports. See if one discharging more oil than the others.
 
#19 ·
If one discharges more oil than the other ones, what causes this, and what does it mean? Injector o rings are new. And I don't have the kit to dead end the pump. And I'm fed up with the diesel shops charging a fortune just to open the hood.

Anyone wanna buy this truck??
 
#20 ·
If one injector is just dumping oil. It's bad. Causing low pressure and it won't start.

To dead head the pump. Head to you local hydraulic shop and tell them you need to tee together two male -05 orb fittings and need to add a 3k gauge.
 
#21 ·
I hate to be the bearer of bad news but do a little searching of Pensacola diesel.... I don't have the answer to your problem but have see many threads bashing these guys for horrible quality you might want to start troubleshooting the items purchased there
 
#22 ·
There's reason why I asked about them. A little over a year ago, the mechanic that replaced my hpop, got it from them, but he had to replace it 3 times until he got a good one. The IPR he got from them, failed as well, It got stuck. So, I'm wandering about the hpop now. Of course both are out of warranty now, and I don't even want to deal with that same mechanic. HE SUCKS!! I wish he could read that!!

I haven't been under the hood since Sunday.

Thank you all for your replies.
 
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