2001 7.3 High Pop Empty
Lead Driver
Joined: Jun 2004
Posts: 6,366
Likes: 595
From: Amarillo, TEXAS!
65% is actually not good. It means you're not building hydraulic pressure for the injectors. I think you either have a bad HPOP or, of the HPOP was recently installed, the gear is spinning on the shaft from the bolt being under torqued. Those are educated guesses; it could be other things. Those just seem the most likely based on the data.
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,388
Likes: 6
65% is actually not good. It means you're not building hydraulic pressure for the injectors. I think you either have a bad HPOP or, of the HPOP was recently installed, the gear is spinning on the shaft from the bolt being under torqued. Those are educated guesses; it could be other things. Those just seem the most likely based on the data.
so icp or ipr is not the issue at all? Hpop installed in 2018 from riffraff.
Cargo Master
Joined: Apr 2022
Posts: 3,203
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Correct. Hpop is spun by top of cam gear. Icp tells pcm what psi it's making. Then pcm tell the ipr valve what to do with the reading from icp. Ipr valve is "dump valve". Hpop is constantly making pressure. The ipr valve opens to dump excess pressure back into the crank depending on what the pcm tells it to do. 10% ipr means it's 10% closed so it's bypassing most of the hpo back to crank case. 65% (which is max) is 65% closed.
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,388
Likes: 6
Correct. Hpop is spun by top of cam gear. Icp tells pcm what psi it's making. Then pcm tell the ipr valve what to do with the reading from icp. Ipr valve is "dump valve". Hpop is constantly making pressure. The ipr valve opens to dump excess pressure back into the crank depending on what the pcm tells it to do. 10% ipr means it's 10% closed so it's bypassing most of the hpo back to crank case. 65% (which is max) is 65% closed.
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Cargo Master
Joined: Apr 2022
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Possibly. Hard to say without diagnosing it. Check gear and bolt first. Then they make a dead head test tool that replaces the ipr valve to dead head the pump to see if it makes pressure. Don't just throw a $600+ pump on it without doing more diagnostics.
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
So swash plate pumps don't just quit work very often, and when they do it usually happens catastrophically. Like it's insides become outsides kind of catastrophic. Solenoid valves seldom fail either. The magnetic coil can burn out but even that typically will show signs before just quitting. What can and does fail with little or no warning is wiring and electrical connections. The IPR connector and pigtail are a known trouble spot, and a can fool the passing glance. The wires can actually turn to goo inside the loom. Between age, countless heat cycles, oil/diesel, and the current passing through the wire the insulation can just turn to jelly. The loom has to be removed and stripped back 6-8 inches or so to inspect the wiring for any signs of damage. There is also the possibility of air lock like I mentioned earlier. It wouldn't explain the truck dying on you but it would explain a no start now. As far as the truck dying have we nailed down why the reservoir was empty?