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Discussion Starter · #1 ·
Hey guys, another 6.0 nightmare.

This truck has an SCT tuner, as well as an EGR delete and blue spring.
8 fresh injectors, ARP studs.

Truck was working fine until yesterday, now it will start fine, runs rougher and rougher and stops responding to the pedal until finally it dies.

ICP desired and actual are right bang on, I have no reason to suspect an HPO issue, snaps up and down to pressure with the throttle.

No smoke of any colour, except a light black haze when I snap it WOT at high RPM as I would expect to see. No codes. I hooked a manual gauge up to the bowl and I have 65PSI at idle and WOT, doesn't seem to drop as the truck dies, but it dies as if it it's being starved for fuel.

Recap:
No codes
No smoke
IPR des and actual are good
65psi at fuel bowl
Fresh fuel filters
 

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Whose injectors did you install?

FICM volts (KOEO, cranking, and running)? Do this testing with BOTH a hot and cold engine.

Are the 3 FICM connections firmly seated in the FICM?

OEM fuel filters?

Do a bubble test on the fuel system.
 

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Discussion Starter · #3 · (Edited)
Checked FICM voltages and they seemed good, I'll double check them again this morning now that it cold soaked.
From memory, they were:
11.5, 11.5 and 48 KOEO and crank
13, 13, and 48 running hot

FICM connectors are solid, I did a wiggle test on that portion of the harness with no change.

I'm suspecting maybe a bubble test will tell me more. I'm thinking it may be sucking air before the fuel bowl, since any time I've come across combustion gasses pushing past the copper washer it exhibited a lot of smoke.

Running Fram filters for oil and fuel, same as our other 6.0s with no issue. The only real difference between them and this one is that the tank liner is beginning to come out of this one. We were seeing large amounts in the frame mounted filter, and have upped our filter change schedule on it, yesterday I had the apprentice pull the sending unit on the tank and he said there didn't seem to be any debris on the suction tube. I was out of the shop so I didn't put eyes on it myself.

I also noticed that when it is struggling, engine load is reading at 80-90% while idling. Not sure how relevant that is.


They're UpTime injectors, my local diesel shop that I usually buy parts from told me they're the only ones they use besides the OEM ones and there was a significant enough price difference that we opted for the UpTime injectors.

Edit: Had time to go do some more checks on FICM voltage.
Cold KOEO: 11.5 11.5 48
Cold Crank: 10.5 10.5 47.5
Cold running: 13.5 13.5 48.5
 

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Discussion Starter · #4 ·
Well, I feel a little stupid. Had time to actually spend a little diagnosis on it myself.

Pulled the upper fuel filter and went key on and saw nothing but foam and bubbles coming out the fuel feed. I suspect it's sucking air further back in the system. Driver said they heard a loud bang when before it lost power, I can't imagine what it would have been, but I'm fairly firm in believing that it's sucking air somewhere in the system before the upper fuel bowl.

Unless the 6.0 Gurus can think of something else it might be, I'm going to head down this road and will report back with my resolution.
 

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I would STRONGLY recommend only OEM filters. The OEM secondary fuel filter has an indexing tab and a vent that many (probably most) aftermarket filters don't have. I understand that you have another 6.0L that seems to do OK with aftermarket filters, but the data out there is quite significant in favor of running only OEMs.

I am also suspicious of non-OEM injectors as well. My guess is that your issues lie in one of those two areas.
 

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Discussion Starter · #6 ·
Well we'll get some new OEM fuel filters and start there.

I've always been leery of aftermarket injectors as well, but these guys haven't steered me wrong yet so I'm willing to trust them for now. As of right now my primary suspect is sucking air somewhere before the upper fuel bowl. Unfortunately I'm not in the shop much this week, so it's tough to get to involved in the diagnosis. Will report back as I find more.
 

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Discussion Starter · #7 ·
New fuel filters in, did a bubble test off the return line, yielded very small amounts of air, proceeded with a balloon test off the return lines, DS was good, PS found small amounts of air, so one of the injectors did not seal properly. Frustrating because the truck has been back in service for over a month before this issue presented itself.

Hopefully we'll have time in the shop tomorrow to pull the injectors out of that side and see what's what.
 

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Discussion Starter · #8 ·
For closure on the thread: Found 2 injectors that did not seal, thankfully the driver is pretty on the ball and didn't keep pushing the truck. Will replace the injectors and we should be good again.
 
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