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Discussion Starter · #1 ·
05 Harley 6.0 170k miles. Fires up fine when cold.
When hot it is hard to start the truck.
I used the pressure tester to the icp port and found stand pipe upper part had leaky orings and replaced them
Problem came back a day later only to be the same thing on the other side, replaced those orings as well.

Now when hot still hard to start. Sometimes it takes a minute or two to cool down then will fire with some long cranking. Icp confirms apx. 330 psi until it builds up past enough to fire up.

I removed ipr and pressure tested that way when it was cold and found nothing immediately. If I waited long enough I could hear some sizzling at the fuel injectors but figured that was normal as the spool valves probably leaked the oil out over some time.

This time I tested it hot again at the ICP port. I did all of my testing with the ipr energized at 20-25% duty cycle, and again at 90%. I can hear slight noise out of both oil fill, and crank vent into turbo inlet. I'd say the noise is comparable to the sound you make when you sigh (it's that quite).

I'm not sure what to do here. Open to all help and suggestions.

Thank you.
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Testing for a leak with the IPR commanded to only 20-25 %Duty Cycle will tell you nothing. You will blow air into the crankcase that way, unless you just happen to have the IPR valve STUCK in the completely closed position.

You still have a leak somewhere, and it might be through the IPR valve. Commanding it closed won't guarantee that it is closed.

Might be worth getting the fitting that enables you to air test through the IPR valve port (the fitting is designed to block air flow to the crankcase). If the leak goes away completely, then the old IPR valve is the culprit.
 

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Discussion Starter · #4 ·
Yeah I understand at 25% however I only used that so I could leave it energized. Perhaps I shouldn't have done it that way. Regardless I did do it again at 85 with the same results. I'm about to pull the turbo and try it again. I think I put an ipr in this truck already but I do have another I could throw at it.
I have both pressure testers. Most of my testing has been done at the ICP port but I believe I had done it once at the ipr as well
 

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Discussion Starter · #5 ·
Just finished testing at ipr valve and eventually the hissing started. Both sides down low not very loud like the usual upper stand pipe seals. You can tell it's coming from lower in the block so it would seem.
However I could hear gurgling at what I'd believe was the oil filter housing.

I find that odd since I used the fitting and ideally it's suppose to seal off the flow from going backwards. Do you have any input on that?
I'll pull the fitting back and check the oring after lunch
 

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Sounds like an HPOP.
 

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Discussion Starter · #8 ·
So I grabbed another hpop off the shelf that is supposedly good, mocked up a block off plate on the outlet of the pump and used my ipr pressure tester and still it's back feeding into the inlet of pump.

Would that mean that the test tool has an issue and the pressure is going around the oring on the tool and back into the inlet?
 

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Is your oil filter removed from the housing?

Also, you can rotate the pump and see if there is any change in the backflow through the HPOP.
 

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Discussion Starter · #10 ·
It is not.
I've watched a few videos on hpop bench test and found that there shouldn't be air flowing back into the inlet. So I'm going to say this pump is on its way out along with the on off my self. The one that's in the truck may be worse, I haven't removed it yet.
 

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Back to post #7
 

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Discussion Starter · #12 ·
Lol. For sure, you called it. I was thinking that from the beginning but I wasn't going to throw anything at it until I could physically figure out why. Now I know gurgling into filter housing is a bad hpop when testing at ipr. I think I read that some place on all of the internet ha.

Thank you so much for giving me some insight here.
 

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Discussion Starter · #13 ·
I pressure tested @ the ipr for at least 5 min straight with no audible leaks. Put it all back together and get it nice and hot. I'm still having long crank times but does fire. It takes 10 or more seconds while hot to fire.
I just don't understand. Going to put another ipr in it tomorrow morning.
 

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Sometimes it takes a while t get the air out of the system.

Ford recommends several spirited accelerations and 15-20 minutes of highway driving IIRC.
 
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Discussion Starter · #15 ·
Well, back at it again. I let the truck sit for a while so I could get some other stuff done.

Ipr did not fix it. Hpop did not fix it.
Starts up super easy when cold.
Starts normal after regular driving.
Hard starts after spirited driving.

I put a manual oil pressure gauge on the lpo system and couldn't get a reading after the hard starting.

Checked the lpo relief valve and everything is fine there.

Any more recommendations, I'm running out of ideas..
 
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