Hard/No start when hot

David N · Jul 16, 2015

So I've done some reading and I can't find a straightforward answer. So here goes:

The truck is in my sig, I have just recently in the past week installed a Gen 3. My problems do date back before the install, but it seems the Gen 3 has amplified them. Also I will add, sometimes it starts fine when hot. Its almost sporadic it seems. But it will start hard more times than not.

My truck has a hard start and now since the Gen 3 install, occasionally a no start issue. Before the Gen 3, it would always start perfect when cold, but when hot, I would have to turn the engine for 10+ seconds and it would sound awful when it finally did fire. It would knock horribly and run ragged for a couple of seconds then smooth right out. (This is honestly how I imagined a Gen 3 startup) It always starts right up when cold. For the longest time (years) my hot starts have been getting worse and worse. I have changed injectors during this period and it still seems like it is getting worse.

It does still have the original IPR and ICP sensors that came in the truck when I bought it 6 years ago. This IPR has 80k miles on it, (That I know about) and has only been removed once. When I did remove it, I noticed a torn oring so I assumed it was my problem. I replaced the oring and it made no difference.

I have noticed the past few times it has done the no start scenario, the oil pressure gauge in the truck will not come up to indicate it has oil pressure. But if I keep turning the engine (for 20+ seconds) it will eventually fire. It has done this 3 or 4 times now and I'm just waiting for it to strand me somewhere.

Current Duty cycle at idle is around 10-12% and around 550 ICP. I have yet to get my AE on it when it is in its no start mood so no readings there. I will also add that I have NOT ran the secondary oil line to the reservoir for extra feed oil yet. I honestly haven't seen any need because my truck hardly lopes when started so I thought there was no need. Could this be contributing to my no start?

So my question is, could this be IPR related? Would a bad IPR cause a hard hot start? Or does it sound like injector orings maybe? The injectors were last at Full Force diesel around 2.5 years ago. Maybe I got a bad batch of orings? If not, what else should I look at?

Arisley · Jul 17, 2015

I have noticed the past few times it has done the no start scenario, the oil pressure gauge in the truck will not come up to indicate it has oil pressure. But if I keep turning the engine (for 20+ seconds) it will eventually fire. It has done this 3 or 4 times now and I'm just waiting for it to strand me somewhere.

Get a mechanical gauge on there and get as real oil pressure reading. Might think about a compression test also.

Get AE on it and see how ICP and DC are while driving it. So, are you still running the same old IPR on there as when you had your stock HPOP. When you first get a no start condition, pull the plug on the HPOP reservoir and dip a stick/screwdriver/hunk of wire coat hanger in there and check oil level. First place I would suspect if it is low is IPR.

If you get a no start, and leave it and walk away, if you come back a few hours later, does it bust right off and run fine, does it bust right off and run like crap for a few seconds, does it long start and run like crap, does it long start and run perfect?

Have AE hooked up when verifying these symptoms, watch volts, Low pressure oil, ICP and Duty Cycle. I am suspecting either a bad IPR or a bad LPOP.

David N · Jul 17, 2015

Arisley said:
Get a mechanical gauge on there and get as real oil pressure reading. Might think about a compression test also.

Get AE on it and see how ICP and DC are while driving it. So, are you still running the same old IPR on there as when you had your stock HPOP. When you first get a no start condition, pull the plug on the HPOP reservoir and dip a stick/screwdriver/hunk of wire coat hanger in there and check oil level. First place I would suspect if it is low is IPR.

If you get a no start, and leave it and walk away, if you come back a few hours later, does it bust right off and run fine, does it bust right off and run like crap for a few seconds, does it long start and run like crap, does it long start and run perfect?

Have AE hooked up when verifying these symptoms, watch volts, Low pressure oil, ICP and Duty Cycle. I am suspecting either a bad IPR or a bad LPOP.

Im glad you replied Andy...

Yes, when I leave it for a while after driving it, say probably an hour or so, it starts just fine. I will add, ever since going to these 200% nozzles, I've always a lope on startup whether hot or cold start. But this lope is amplified 5x during hot starts.

Also, yes, its the same IPR that came in the truck when I bought it 6 or so years ago.

Duty Cycle and ICP during hard acceleration with the Gen 3 is now 3500 psi at 45% DC I believe (Ill have to check) but I am certain the Gen 3 is working correctly.

Arisley · Jul 17, 2015

Not doubting the GenIII, that's a dependable unit. Doubting the IPR. Possibly the LPOP. Whose injectors did you put in there, they are a possibility, but if you got them from somebody as reliable as the GenIII, that would not be the issue. Unless of course, it's been long enough ago to get caught up it that bad batch of o-rings, or you slapped them in the holes dry and tore an o-ring.

79jasper · Jul 17, 2015

Sounds like what my brothers truck did when the IPR went.
But there's a million and a half things that can cause the same symptoms. We did injector orings first, then IPR orings and cleaned it, still the same so he finally just bought a new IPR. I think the solenoid was bad.

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lincolnlocker · Jul 18, 2015

id start with a new ipr but as andy said, get a good gauge on it for lpo to see what thats doing.

live life full throttle

David N · Jul 18, 2015

Injectors are from Full Force, and I got them around 2.5 years ago.

So I guess Ill be buying a IPR then. Ill give that a whirl. Thanks guys.

qcfarmer · Jul 18, 2015

My truck was doing the same thing. I had a spare ipr so I swapped solenoids and it solved my problem (and didn't make a mess in the valley).

David N · Jul 18, 2015

Thanks guys.

pdumont01 · Jul 18, 2015

Could be the high pressure oil rail plugs. I've seen that a bunch of times. If you can air test it when it is hot while powering up the solenoid you can hear where it leaks from, may help you avoid throwing parts at it. What year is the truck?

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02BigD · Jul 18, 2015

David N said:
So I've done some reading and I can't find a straightforward answer. So here goes:

The truck is in my sig, I have just recently in the past week installed a Gen 3. My problems do date back before the install, but it seems the Gen 3 has amplified them. Also I will add, sometimes it starts fine when hot. Its almost sporadic it seems. But it will start hard more times than not.

My truck has a hard start and now since the Gen 3 install, occasionally a no start issue. Before the Gen 3, it would always start perfect when cold, but when hot, I would have to turn the engine for 10+ seconds and it would sound awful when it finally did fire. It would knock horribly and run ragged for a couple of seconds then smooth right out. (This is honestly how I imagined a Gen 3 startup) It always starts right up when cold. For the longest time (years) my hot starts have been getting worse and worse. I have changed injectors during this period and it still seems like it is getting worse.

It does still have the original IPR and ICP sensors that came in the truck when I bought it 6 years ago. This IPR has 80k miles on it, (That I know about) and has only been removed once. When I did remove it, I noticed a torn oring so I assumed it was my problem. I replaced the oring and it made no difference.

I have noticed the past few times it has done the no start scenario, the oil pressure gauge in the truck will not come up to indicate it has oil pressure. But if I keep turning the engine (for 20+ seconds) it will eventually fire. It has done this 3 or 4 times now and I'm just waiting for it to strand me somewhere.

Current Duty cycle at idle is around 10-12% and around 550 ICP. I have yet to get my AE on it when it is in its no start mood so no readings there. I will also add that I have NOT ran the secondary oil line to the reservoir for extra feed oil yet. I honestly haven't seen any need because my truck hardly lopes when started so I thought there was no need. Could this be contributing to my no start?

So my question is, could this be IPR related? Would a bad IPR cause a hard hot start? Or does it sound like injector orings maybe? The injectors were last at Full Force diesel around 2.5 years ago. Maybe I got a bad batch of orings? If not, what else should I look at?

Choppy start up ok, but never knocking sounds with the Gen3. Like starting a big block with an aggressive cam...

Arisley · Jul 18, 2015

pdumont01 said:
Could be the high pressure oil rail plugs. I've seen that a bunch of times. If you can air test it when it is hot while powering up the solenoid you can hear where it leaks from, may help you avoid throwing parts at it. What year is the truck?

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That would be noticeable by big puddles of oil under the truck.

pdumont01 · Jul 18, 2015

Yeah i realized it was a 7.3 after the fact. I would lean towards a bad ICP sensor mine did the same thing. 6.0 is what I thought it was.

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