I tested for HPOP leaks thru the IPR sensor location, and didn't have any leaks. I got the new IPR screen on the sensor and the sensor installed along with new battery cables, grounds and positive, and a new oil filter. Now the truck won't start at all, it will turn over but not fire up. It was getting dark but I did get a few values.
IPR KOEO - 14.%, Cranking up to 75%
ICP KOEO and cranking- 0 unplugged and cranking 950 psi
FLP 11.5V
FMP 49V
I removed the oil filter cap after cranking for a while and the filter housing was full and wouldn't drain until I removed the filter. I reinstalled it then cranked a while and rechecked it, this time it drained before removing the filter like normal. Prior to these mods the IPR (never seen above hi 50s) and ICP values were in range. I pulled the IPR relay after cranking and it was a tad warm, is that normal? Is it possible that the IPR sensor went out?

 

Just checking when you first pulled the IPR valve and didn't find a screen, did you look inside the hole to make sure the old screen wasn't stuck inside?

 

That is in fact what he found. We have had a few conversations in PMs. I believe he will be updating this thread shortly.

 

When I checked the first time I used a magnet and it didn't catch it. On the second round I used a pick and yep it was still in there, thank god it didn't damage the new screen.

After getting it back together it took a while to get it started and had a misfire on #8 cylinder. When I put it back together the injector plug wouldn't stay locked thus I had a hard time getting it plugged in, come to find out one of the prongs was bent and not fitting into the female end. I installed a new injector but didn't finish buttoning everything up yet. I am having trouble finding the correct torque values for the fuel rail bolts. I have seen anything from 10 ftlbs to 18 ftlbs. Anyone know what the correct value is for a MY 2004?

Below are few PIDS at idle once the IPR was cleaned with a new screen and new battery cables.
FMP 49.5
FLP 12.5
ICV 1.07
IPR 26.4
ICP 844 once engine was warm settled at 590 ish

There are some very knowledgeable folks on FTE who are not afraid to share what they know about the 6.0. I would like to thank Mark and everyone else for the help.

 

A torque wrench to measure that value will be in lb-ft.

 

Thank you Jack, I sent Mark a PM last night and his answer matched yours so now I am confident on what I need to do.

 

Just to verify the Standpipe and dummy plug torque values should be 60 lb ft correct? I saw 33 lb ft but seemed like the consensus was 60.I figured while I had the fuel rail off, even though I didn't have a leak, I would change these out. The dummy plug and standpipe were the 1/2" square drive type. The units I purchased come from the dealer and have the 12mm allen head.

 

It's the next line down on the table I posted for you. The hex are the new parts, the square the original.

 

My apologies I missed it. Thanks.

 

Finally got the truck back together, what I have done thus far is replace both GPCM pigtails, replace #8 injector, replace IPR screen, replaced the driver side dummy plug & standpipe, & replace battery cables. After purging the air the engine fired up and ran smooth everything looked good. After idling for about 5 min the oil pressure gauge on the dash dropped to nothing. I stopped the engine and checked the oil restarted it and the gauge went to normal for a few seconds then back to nothing. If you rev the engine slightly the oil pressure gauge does climb back to normal. I did the test with the oil filer removed and cranked it with the starter wire. Crank time to fill without filter in place was 9 seconds and with valve closed almost 5 seconds. The filter was completely soaked in oil. Question is the new standpipe supposed to come apart? When I tapped the valve cover bolt I removed the fuel rail and the standpipe came apart, I didn't remove the lower half from the head and just replaced the rail and top portion once done with the tap. Both halves seemed to lineup when I torqued the top section, is it possible it did not and could this cause the low oil pressure to drop? The link below is what my gauge is doing. I am using OEM filter and cap.

 

I have trouble believing that the standpipe could be enough of an issue to cause the low pressure oil pressure to drop. You can damage the o-ring on re-installation, but I would expect that to show up as a leak in the high pressure oil system and not show up in the low pressure oil system.

Are your ICP actual and ICP desired tracking well at a reasonable IPR % duty cycle?

From all you have posted, the "dropping off" of the dash gauge is more likely to be an issue with the HPOP suction o-ring or the pressed in ball bearing (IMO anyway). The low pressure indicated on the dash gauge is telling you that the issue is probably on the suction side of the HPOP (not as likely to be on the high pressure side).

I wonder about your issues with the screen from the IPR causing a significant restriction (or the standpipe that was changed out) which might have had a "pressure effect" on the HPOP ball-bearing (suction side).

 

I was thinking about pressure testing the HPO system again. On the first and second test, pre dummy plug and standpipe replacement, I didn't hear leaking anywhere. I am not sure how to determine this "Are your ICP actual and ICP desired tracking well at a reasonable IPR % duty cycle?" Can you explain?

To update everyone since the last post I pulled the oil pressure regulator, everything looked good there, and also changed the oil pressure switch. The oil gauge does the same.

 

There are PIDs for each of those parameters (ICP, ICP Desired, IPR % Duty Cycle). Watch those PIDs when the dash gauge is dropping.

 

PIDS with Cold engine:
ICP - 734 psi
ICP Des - 740 psi
IPR % - 29.69

After 7.5 min of running gauge dropped to 0
ICP - 580 psi
ICP Des - 584
IPR % - 24.61
Also getting the following codes now:
P0611 - FICM Performance
P1378 - FICM Supply Voltage Circuit Low
P0670 - Glow Plug Module Control Circuit Still getting this after changing the GPCM and the pigtails.

 

You don't have a higher voltage FICM do you?