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You have to think two fold. What is the ECM electrically commanding and what is the IPR doing. A few years ago I was towing my 5th wheel when all of a sudden my fuel pedal got real touchy and I heard the injectors chattering. A condition of when a tuner raises ICP. I hooked up my AE scanner and the ECM was commanding 700 psi which is the pressure at Idle. But the chattering told me otherwise. I then hookup 3000 psi mechanical gauge. A 5000 psi gauge would have been better but 3000 was all I had. As soon as I cranked the truck the 3000psi gauge maxed out. A stuck IPR was indicated. I replaced the IPR and ICP sensor. Was good to go.
 

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If I remember correctly the ICP has to be at 500 psi before the injectors will fire. You can unplug the ICP sensor and the ECM will default and run the engine. If the engine starts then the ICP sensor is bad.
 

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Discussion Starter · #24 ·
I unplugged the ICP last week and it still didn't start. When I get home today ill try to read the ICP pressure while its cranking
 

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A hydraulic pressure gauge installed in one of the HPOP head ports will be most telling. If you have 500 psi then its not a HPOP issue. If no or too little pressure then you have to determine if its HPOP or the IPR. The IPR is both mechanical and electrical. I would unplug the ICP and let it default. There are instructions on how to take one apart and clean and probably an ohm value for the coil as well.
Tractor Supply should have a hydraulic gauge which only has to be 1000 psi if you will only run it at idle. But 4000+ gauge would be needed if you want to check pressure past the 700 psi idle level. You will need a 1/4 hydraulic hose with npt ends 2 or 3 feet in length with necessary fittings to connect gauge(1/4 npt) and you will need a #4 oring boss to pipe fitting to connect the hose to the head port.
 

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I have never had to check the HPOP directly. I have ran a DieselSite HPOP since 2013. I highly recommend them if you have to go that way.
Install gauge and see what you have. Work back to IPR ($180ish). Then HPOP ($800ish)
There is a screen in the HPOP oil reservoir. And verify that the oil level is 1'' below the top at the port on top.
 

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Discussion Starter · #29 ·
Okay great, I've got a pressure gauge from my last 7.3L I'll screw that in tonight and check my hpop pressure. oil level is full or at least an inch from the top
 

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Discussion Starter · #30 ·
Physical and electronic gauge (running off of ICP) both has HPOP pressure around 350-420 when cranking. Lower when hot. I thought maybe its the IPR but when i unplugged it and cranked the motor i got no pressure what so ever. the IPR plug had 12v to it when key was on. Could this be the HPOP? Is there any more tests i could do specifically towards the hpop? I don't want to spend the money if I don't need too..
 

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If you can't build pressure to 500 psi, the engine won't start. Unplugging the IPR will cause no pressure whatsoever, because it needs voltage to close the relief port to build pressure. You could wire a pigtail to put 12V to the IPR from the battery which should cause the HPOP to go to MAX pressure. But don't do that for very long as you might burn out the IPR coil.
You either have an IPR that's sticking open, or possibly injector o-ring leaks.
You can check for o-ring leaks by blocking the hoses to the heads (one at a time). If pressure builds then, you have a leak on the bank that you blocked off. Blocking both hoses checks the IPR/HPOP combo. The only way to tell if the HPOP is bad is to install a known good IPR for the test. You need adapter fittings for blocking hoses and installing the ICP sensor on the hose when blocking the driver's side hose.
 

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Discussion Starter · #32 ·
by unplugging the IPR and having No HPOP pressure wouldn’t that confirm a good IPR? Injector ORings are all brand new and should not be leaking whatsoever. The IPR had 12v to it when cranking
 

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Remember that things can go bad in the o-ring install. A bad o-ring is still a possibility
 

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Discussion Starter · #34 ·
Would taking the lines off the HPOP and putting them up and filling them with oil tell me if my injectors are leaking? Or is there really no way to tell unless you take them all out?
 

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by unplugging the IPR and having No HPOP pressure wouldn’t that confirm a good IPR?
Not necessarily. Unplugging the IPR totally disables it. If it's unplugged, the HPOP CAN'T build pressure.
Would taking the lines off the HPOP and putting them up and filling them with oil tell me if my injectors are leaking? Or is there really no way to tell unless you take them all out?
I suppose that would work, but there isn't much pressure available with the lines. You'll get maybe 1/2 psi at the injectors which may not be enough to make a bad o-ring leak. It may take weeks to identify if one side is leaking.
The way to check for leaky injector o-rings is to block off the lines to the heads like I mentioned above.
 

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Discussion Starter · #36 ·
Okay i just made a new hydraulic hose for pressure testing the hpop today. How will i know if the ipr is working or not?
 

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Like I said above, the only way to know if the IPR or HPOP is at fault is to install a known good IPR.
 

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Discussion Starter · #39 ·
I know it’s been a week but things at work have been crazy, I bought a new IPR from Ford along with a dummy plug with an air fitting on it to test for leaks. I first put the plug in and put pressure to it listening for leaks and looking under the valve covers I took off. No visible leaks and there was no noise either. I checked for bubbling in the fuel bowl too. The bubbling that I DID find was in the HPOP reservoir, is that common? Or is that just another reason why I should get a new HPOP?
 

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Not knowing how you hooked up your air fitting, there's no way of knowing if that means your HPOP is bad. If you want to check for a bad HPOP, you need to block both hoses going to the heads (plugging the HPOP output), and with a 3000 psi pressure gauge on one hose, crank the engine while applying 12V across the IPR coil. It should nearly peg the gauge when the HPOP relief valve opens. You can do that test with both your original IPR installed and the new one, which will tell you whether the IPR is at fault or the HPOP if it won't get above 2500 psi. Your air test should be on the heads individually with no connection back to the HPOP.
 
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