2004 Old style HPOP, new style Fuel rails.
Pulled Injectors to fix stiction issues. Truck ran fine for 20 miles while I bled the air back out. Now it has a problem that I cannot figure out. It runs perfect while cold. Once it hits about 120 degrees #1, #2, and #8 and occasionally #6 injectors quit working. I thought maybe it was an injector issue, So I replaced those 3. Still #1,#2,and #8 will quit after running for a few minutes. If I rev the motor and hold it to about 2000 RPM all the injectors come back to life and the motor smooths out.
Originally I thought maybe an electrical issue. After the injectors quit I can still control them with IDS. Injector Buzz test. Fuel pressure is 55 at idle and drops to 45 WOT. I have air tested and the system had a few small leaks. those are now fixed. The problem persists. I have Re-sealed the HPOP. FICM voltage never drops below 47.5. IPR is at 27% at idle. One thing I did notice is that the IPR % will bounce around a little after the truck warms up. It never moves much, but it never stops moving. While cold the IPR % stays relatively stable and doesn't move much. I have swapped the IPR valve with a known good one, Unplugged the ICP sensor, Swapped The ICP sensor with a known good one, Fixed the wire Chafing on the ICP plug, bubble tested at the Fuel filters. I pulled all 8 injectors and double checked everything, Put new orings and copper washer on and re-installed. I have read some threads with similar problems, but have never read what the solution was. I am going to reassemble it tonight and warm it back up and do another air test. I have IDS available for further testing just need a direction on where to go. Also the only code is #1 cylinder contribution. Relative compression is good. Truck had a funky wix cap. Has OEM oil filter and cap now with a fresh Delo oil change.

 

Just a stab here, but could it be nipple cup seals?

 

The nipple cup seal pass the air test. I suppose it could be, but as far as testing goes they pass.

 

Tonight I am going to run it until it gets hot. I am hoping with the small leaks here and there I fixed that it will run fine. If not I plan on pulling the oil filter and doing another air test while its hot. I am thinking if the HPOP is weak it may send the air through the filter. Any other suggestions before I complete pulling my hair out? Keep in mind my hair is thinning anyhow!!!

 

Imo your on the right path. Have you ran it with the icp unpluged? Have you air tested it yet with the oil filter housing open?

 

If you have another 6.0 available to you, it could be worth transferring the FICM to that truck to see if the issues follow the FICM as well. Logic board issues can periodically cause your symptoms.

 

I have air tested it with the filter out. The problem only shows up when its warm so I need to try it again at temp. I have ran it with the ICP unplugged, and also switched it with another I have laying around.

Cheezit thank you for the reply. With your help I will figure this thing out!!!

 

I can pull the one off my truck and give it a try.

Thanks for the Reply, I am loosing motivation on this thing!!!!

 

if the IPR is showing 27% at warm idle... you have a leak somewhere. It should be near 21-23%, not 27%.

 

now i am thinking this could be a PCM problem. After putting the truck back together I cycled the key. The injectors buzzed wonderfully. The problem is they do not stop buzzing now. I thought maybe it was a FICM issue like Ed suggested so I pulled the one off my truck and put it on. The injectors still buzz and wont stop. The only way to stop the buzz is to shut the key off. I dont think starting the truck with the injectors buzzing sounds like a great idea. Could it have lost programming after being without power for days? this truck and PCM is 12 years old. Any thoughts?

 

did an Injector buzz test ( while injectors were buzzing ) the buzz shut off after about 30 seconds and the buzz test completed. PCM fail. I did the test again without shutting off the key and the PCM passed. Cycle the key on and off and the Endless buzz continues.

 

Any ideas on what could make the Injectors buzz for an extended time? Could it be a wiring issue or is this a PCM problem. Keep in mind swapping out a good FICM did not cure the problem. I am feeling like swapping out the entire harness and the PCM at this point. There is a gremlin somewhere.

Also there are no codes present with IDS.

 

I'd replace the harness first

 

I have been trying to sort this out. Does anyone know what would cause the injectors to clatter and not stop? I have ruled out the ficm. I removed both wiring harnesses ( injector and Main ) and ohm tested every connection and found no problems. I am at my wits end with this truck.

 

Just a shot in the dark but I had a similar problem and when I torqued the injector clamps down the second time, i torqued it to 30 lbs/ft instead of the 26 and it fixed it. I'm not positive but I think there was something that recommended increasing that torque to 28 instead of 26 anyway. Hope you get it figured out. I know it's frustrating.