It very well could be the IPR, but clogging up the screen doesn't cause LOW pressure since the IPR is a dump valve (controls pressure by dumping high pressure oil back to the crankcase). Now if debris got through the screen and the valve is sticking open, then yes.

Finding debris begs the question as to the source of the debris!! And is it magnetic?

Just an fyi - there are a lot of cases of early HPOP failures. The only reliable HPOPs to buy are the ones from DieselSite or from CNCFab. Hopefully the HPOP is fine though.

You can do a leak test w/ air, or just install a new OEM HPOP (from a dealership) and hope.

 

Yea, I am kinda stumped, I put a new HPOP in the truck in April. I purchased the HPOP from CNC machine. I have been thinking it might be the problem. I plan on doing an air test on the truck. Where else could an early 6.0 have a leak in the high pressure oil system other than the HPOP? Diesel tech Ron’s videos say the early 6.0’s is almost always the HPOP, yet the HOPO I purchased was from a reliable source, CNC Machine And I installed it correctly…

 

I would think that the HPOP is fine. Definitely would suspect the IPR before the HPOP from CNCFab.

Did you install a new J-Tube?

 

Yes, I think I purchased it from Rudy’s diesel. After I installed the HPOP, the truck ran amazing for the entire summer up until I sold it. I feel terrible for the gal who bought it from me. I will fix it for her, it is the right thing to do!

 

BTW, thank you for the help!

 

I expected the CNC machine HPOP would not fail. I hope it is something simple. BTW, I did get a p2623 code so I will be inspecting the wiring harness fo starter.

 

That code has nothing to do with your starter. It is a VERY helpful code.

In fact starting w/ posting any/all codes is best!

P2623:

Open/grounded IPR circuit. Stuck IPR. Loose connection. Shorted out IPR. or shorted out connector/wiring.

Pull back insulation on the connector wiring to inspect. It is hot behind the Turbo and that heat takes its toll on the connector, and sometimes on wiring insulation. If wiring and connector look good, your issue is the IPR.

 

Sorry, I meant to say “for starters”.

 

So, I went out today to try and find the fix for the crank no start on my old truck. I used my open circuit tester and found no brakes in the wiring to the IPR. I found a broken ground wire on the wiring harness on the rear devices side of the engine by the FICM & repaired the ground. Still, crank, no start.
I had FICM sync = 1
FMP 11.5v
ICP v = .6 during crank
HPOP = 350
IPR = 83.9

All I can think of is replacing the IPR and/or doing a air test to the high PSI oil system. I checked the connector that leads to the IPR; red is on the left and red/yellow is on the right. Still have the p2623, p0603 & p1000. The truck has always had the P1000 and has never had any issues???

I am perplexed! I purchased the HPOP from CNC Machine and Installed it correctly, I guess the HPOP could be the problem. The truck ran great all summer. After I installed the new HPOP . I sold it to this gal who is a really good person and on her first trip in the truck….it has this crank no start issue. I feel terrible and don’t want to leave her high and dry. I’m banging my head trying to fix this crank, no start issue.

Any help would be greatly appreciated!

 

Koeo= .24 icpv

ko while cranking = icpv .6.

this is concerning, yet I do not completely understand. From what I’ve read, icpv should be 1.9ish while cranking. The highest voltage I have seen is .6v which is either a bad sensor or low high psi oil pressure?

 

The ICP sensor is probably good. The way to rule out a bad ICP sensor is to unplug it. If it doesn't start w/ the ICP plugged in, but does unplugged, then it is probably a bad sensor.

As I posted earlier, you almost certainly have an IPR issue (since its wiring/connector appear good, the valve is next in line of suspects) - Also, aftermarket IPRs are a BAD decision, but people do what they feel is right ..... You can check the resistance across the two IPR wires and post what you find.

If you want absolute proof of a bad IPR, then do an air test through the ICP sensor port, command the IPR closed by applying 12V, and when the air flow doesn't change after commanding the IPR closed, you know the IPR is bad. P2623 is almost always properly indicating a bad IPR (or its circuitry) though - circuit codes are not typically thrown for no reason.

I suppose there is a very slim chance that another system short circuit is affecting the IPR circuit (switched power circuit from fuse 22). Typically a shorted out fan clutch harness (because the wiring was not kept out of the fan blades) can do this. Rare cases an EGR valve MIGHT do this. The fan clutch can be unplugged for just to see if the engine will start, and if it does, then immediately turn it off and fix the fan clutch or its harness. The EGR valve can be left unplugged indefinitely. Typically these issues will cause a no-crank though, so I would not expect it to be your issue.

The CNCFab HPOP is not your issue.

 

Mark, Thank you for the help. I was under the assumption that the IPR at 84.7% and HPOP getting no higher than 360psi was either an IPR valve or a high psi oil leak. The IPR I pulled out of the truck had no visible damage to the screen and no contamination. I replaced The IPR with the original IPR I pulled out of the truck years ago. I cleaned this IPR and put a new gasket and upgraded screen filter on the IPR and placed it in a sealed box A few years ago. I still have been getting the 2623 code with both IPRs.
Ohms read 5.7 when I made contact with each terminal.

Question regarding Pigtails. Is there a picture to show which side is of the pigtail is power (red), and which side is the signal (yellow/red)? This may seem like a simple answer, yet, it is also can be confusing depending on how you are looking at the sensor.
So, if I pull the IPR and hold the tip so it is pointed downward & I am looking directly at the connector, is the power (red) on the left side of the connector facing me? Signal wire (red/yellow) facing right?

I am just trying to figure out what is causing the crank no start. Initally, the problem seemed to be a crank, no start when hot. The truck was running while towing a horse trailer. She stopped at a tire shop to check air psi in the trucks tires. Turned off the truck and it would not start. The truck was left at the tire shop for the weekend & one mechanic looked at the truck and had unplugged the oil sensor, then reconnected the sensor. The truck started, unsure if it started because it was cold or if disconnecting the oil psi sensor caused it to start. I have no idea which oil sensor the mechanic was talking about? It might have been a sensor on top of the oil cooler or the ICP? The new owner was able to drive 30 mile to get the truck home. Then, she Turned it off, attempted to start the truck back up and it did not start. I came over to look at the truck and had few days later and the true started right up and shut it off after 10 minutes. Then it would not start up once it was warm. Since then, I had swapped IPR valves and now the truck will not start at all.

Once again, Thank You for the help!

 

one more thing, Koeo; I can hear the fuel pump and good injector clatter. Also, LPOP seems to be good. Oil gauge rises after 10 seconds of cranking & I cranked the engine while looking into the oil filter housing (removed the oil filter) And oil filled as expected.

 

Most people can't hear the fuel pump. They hear the vacuum pump and think it is the fuel pump.

You can try watching the secondary fuel filter fill with the key on. It is a two person job because it will fill fast (if all is normal with it), and will overflow if the key is not QUICKLY turned off.

Remember the IPR % Duty Cycle is a command only. It does not necessarily indicate valve movement. AT 84%+ command, it just means that the HPO pressure is less than desired.

If you didn't clear the codes in between switching, then you can't be sure that both IPR's are giving you the same P2623.

I posted a few unusual things to look for (fan clutch wiring and trying to run w/ EGR valve unplugged). DId you follow the suggestions?

The screen plugging is not an issue for low ICP pressure since the IPR valve is a dump valve. It pulls oil through the valve to dump it to the crankcase when the pressure is higher than desired. That said, particles passing through the screen can cause it to bind and stick open. It is not really possible to clean the internals of the IPR, unless you are a machinist.

The oil pressure sensor on the oil cooler will not affect starting. It is only wired up to the dash gauge.

The IPR valve should function whichever way the wires are installed since it is merely a duty cycled valve.

That said, this is how it should be: Connect B+ to the RED (Pin A), and B- to the YELLOW/RED (Pin B) to close the IPR valve. To identify pins A and B, orient the connector with it facing towards you, wiring at the back, with the wider part of the connector that has the rounded edges on the top. Pin A is on the left, Pin B on the right.

I recommend you verify that there is 12V power on the red wire w/ KOEO (switched power).

The valve is operated off of a duty cycled ground connection. The PCM is what applies the ground circuit (Duty Cycled action). Your ground wire may be shorted to ground constantly - this will cause a high circuit code. It would be beneficial to make sure that the (B-) circuit is in good shape between the IPR and the PCM connector. I do not know the pin number for the 2003 model center PCM connector. On my 2006 it is Pin #2.

 

Thank you for the help! I do not have the truck at my house so I will not be able to unplug the egr and fan clutch until I go see the truck again. I plan to clear the codes again to verify any remaining codes.
I did verify 12v power to the red wire that goes to the IPR with koeo and the signal wire had power when the engine was cranked. I did verify that there was a good connection between the IPR 7 PCM with an open circuit tester and visual inspection of both wires. I will do some research on YouTube to verify the IPR with shop air and putting 12v to the IPR.

Thank You!

 

What signal wire? The IPR does not have a signal wire. There is NO POSITION FEEDBACK on the IPR. That is what I was saying earlier.

It only has power (at all times w/ the key on), and a PCM activated ground to complete the fast acting duty-cycled pulse-width-modified operation of the valve. The IPR Duty Cycle value is a COMMAND ONLY.

There should be NO MEASURABLE VOLTAGE on the ground wire, ESPECIALLY at KOEO.

 

I thought I had read that the yellow and red wire was a signal wire. My mistake. This wire showed no power with koeo. The ground wire (red/yellow) did illuminate the test light when it was in contact with this wire When I crank the engine over. I will have to double check.

 

Update ?