7.3 hpop issues???

Erik307 · Dec 24, 2016

so to start out here I have a late model 99 7.3l psd crew cab short bed with 305k I have had no problems with the truck besides it wont start when cold unless plugged in and replacing the injectors a few years ago. so the problem is I was driving down the highway and it started sputtering like it wasn't getting fuel so I pulled off and checked my fuel bowl and I had no pressure there and couldn't hear the pump running so I towed it home and replaced the fuel pump and filter. after that it wouldn't re start I went as far as bleeding the air from the fuel plugs on the front of the heads and I had fuel there. I noticed while cranking that there was absolutely no smoke coming from the exhaust so that led me to check the injector side beings that nothing seemed to want to fire. everything there checked out so I threw my guage on the high pressure oil side of the heads and I have no more than say 50 lbs of pressure about what the lpop is putting out. I have ordered a new ipr but my question is does the hpop just quit working or gradually get weaker? should I look into a new hpop? when I did the injectors I tested the hpop with manual gauges and I had a steady 2900 psi while driving. I wouldn't think it would go out that quickly but im not an expert by any means. any insight would be great thanks

ToMang07 · Dec 24, 2016

Erik307 said:
so to start out here I have a late model 99 7.3l psd crew cab short bed with 305k I have had no problems with the truck besides it wont start when cold unless plugged in and replacing the injectors a few years ago. so the problem is I was driving down the highway and it started sputtering like it wasn't getting fuel so I pulled off and checked my fuel bowl and I had no pressure there and couldn't hear the pump running so I towed it home and replaced the fuel pump and filter. after that it wouldn't re start I went as far as bleeding the air from the fuel plugs on the front of the heads and I had fuel there. I noticed while cranking that there was absolutely no smoke coming from the exhaust so that led me to check the injector side beings that nothing seemed to want to fire. everything there checked out so I threw my guage on the high pressure oil side of the heads and I have no more than say 50 lbs of pressure about what the lpop is putting out. I have ordered a new ipr but my question is does the hpop just quit working or gradually get weaker? should I look into a new hpop? when I did the injectors I tested the hpop with manual gauges and I had a steady 2900 psi while driving. I wouldn't think it would go out that quickly but im not an expert by any means. any insight would be great thanks

WTS light coming on/off like normal?

Sounds like it could be a voltage issue. Voltage goes too low when cranking the injectors won't fire.

heavydoc · Dec 24, 2016

I believe the hpop needs to put out a minimum of 500 psi to start. 50 is definitely not enough.

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2015sixohno · Dec 24, 2016

Your answer is yes a high pressure pump will just quit working and give up the fight but that doesn't mean this is your problem. I would connect a scan tool and look at IPR duty cycle % and ICP pressures while cranking and see if ICP pressure increases. That will give you more of an idea where to go. If you have 0PSI on ICP I would check that first. Normally the pumps will build something so you should see a change in pressure. Also IPR 85% is wide open for that valve. If it hits 85 (which it never should) and you have 0PSI on ICP you have a high pressure oil leak or a failed pump. If you crank and ICP goes over 450 around or about I would look into possible IDM system short.

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ToMang07 · Dec 24, 2016

heavydoc said:
I believe the hpop needs to put out a minimum of 500 psi to start. 50 is definitely not enough.

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Missed that, thought he was talking about the LPOP

Erik307 · Dec 24, 2016

Forgot to add that i do have wait to start i do have around 300 rpm while cranking swaped out known good icp and idm with no change bench tested the ipr after cleaning and putting the seal kit in it and did not hear or feel the click of the valve operating i have another truck exactly the same but didnt want to swap out pumps i live about 25 miles from town and have no way to get it to town to have it scanned so im kinda screwed on that.

ToMang07 · Dec 24, 2016

Erik307 said:
Forgot to add that i do have wait to start i do have around 300 rpm while cranking swaped out known good icp and idm with no change bench tested the ipr after cleaning and putting the seal kit in it and did not hear or feel the click of the valve operating i have another truck exactly the same but didnt want to swap out pumps i live about 25 miles from town and have no way to get it to town to have it scanned so im kinda screwed on that.

Could try swapping the IPR solenoid. Also make sure the tin nut on the back is tight.

2015sixohno · Dec 24, 2016

Very hard to diag without looking at some type of info from the ecm to give you direction. At that point I would just try IPR. If no change your just throwing time and parts at it without scanning it. I've seen a shorted injector shut one down like that as well so again very hard to say what the problem is. It is very possibly of a failed pump.

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gnxtc2 · Dec 25, 2016

Check the harness going over the driver side valve cover for rub through. Check for corroded wire insulation by the IPR.

Billy T.
[email protected]

rusty1161 · Dec 25, 2016

gnxtc2 said:
Check the harness going over the driver side valve cover for rub through. Check for corroded wire insulation by the IPR.

Billy T.
[email protected]

As Billy said about the IPR harness, here is mine with copper showing on both leads at the connector. I replaced that connector and fixed my no start issue.

Rusty

Erik307 · Dec 28, 2016

okay so I got my new ipr yesterday I put it in last night with that said still no high pressure oil I have 12 volts to the connector for the ipr. I am just not getting any high pressure oil now correct me if im wrong as long at the hpop is working and the ipr is working I should make high pressure oil while cranking no matter what? i did the harness over the valve covers and the uvch and gaskets were replaced when i did the injectors. i guess im really not new to these trucks i have delt with them a lot most of the little things that can cause no start issues i have already checked. im just not firniliar with the hpop after replacing the ipr and still building no pressure and i mean it barely trickles out the fitting on the hpop while cranking im sure it must be hpop unless there is something im not seeing that will prevent hpop from building pressure.:fustrate:

Erik307 · Dec 28, 2016

another thing i know the lpop is working when i removed the plug on the hpop res and turned it over i had oil everywhere in a matter of seconds

lincolnlocker · Dec 28, 2016

unplug icp sensor and try to restart.

live life full throttle

god bless america and the farmer who feeds your fat ass

Erik307 · Dec 28, 2016

Lincolnlocker ive tried that with no change in high pressure oil

97f350stroker · Dec 28, 2016

I didn't read through but did you check the hpop with a mechanical gauge while cranking?

Erik307 · Dec 28, 2016

yes i have mechanical gauge that ties between both heads. right now since i had the hpop off i put it and the new ipr back on and left the lines from the hpop to the heads off and have barely a trickle of oil coming out of the quick connect fitting on the hpop that's leading me to believe that the hpop is not pumping and i have checked the bot for the hpop gear

79jasper · Dec 28, 2016

If you pulled the hpop, remove the front access cover again and make sure the gear is seated on the shaft.

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heavydoc · Dec 28, 2016

79jasper said:
If you pulled the hpop, remove the front access cover again and make sure the gear is seated on the shaft.

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I had one in the shop the owner had replaced the hpop and wouldn't start. Pulled the top cover and saw the gear was cocked on the shaft.

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lincolnlocker · Dec 28, 2016

Erik307 said:
Lincolnlocker ive tried that with no change in high pressure oil

ok. you should still have some sort of hpo. either you have all injectors and ipr stuck open, your hpop internals are no longer in tact, or the gear is off.. you should be reading something more then lpo.

live life full throttle

god bless america and the farmer who feeds your fat ass

Erik307 · Dec 28, 2016

lincolnlocker said:
ok. you should still have some sort of hpo. either you have all injectors and ipr stuck open, your hpop internals are no longer in tact, or the gear is off.. you should be reading something more then lpo.

live life full throttle

god bless america and the farmer who feeds your fat ass

ok i will do some checking tonight i guess that's what was getting me was that i don't even have lpo coming out of the hpop. is there a way to diassemble the hpop and check it out? and i don't believe its injectors because the lines are not connected to the hpop and i have nothing coming out of the hpop and the should be aflood of oil just by cranking it as i have learned in the past.