duramax trouble shooting
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TECH Resident
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Joined: Sep 2007
Posts: 778
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From: East Los Angeles CA
duramax trouble shooting i know this is not the diesel forums but it seems to me that u guys help me out more then they do at the diesel forums, anyone know what could be wrong with this?
well my gf woke up this morning and tried to start the truck and it just kept on cranking over and over and over but would not start, so later when i got home i got starting fluid and made it turn on, and once the truck is on it runs perfect. then when its hot the truck turns on and off perfect so im guessing its only at cold start.... i got the obd2 scanner and egr and air fuel module came on, the SEL has been on ever since i installed the 5 inch mbrp exhaust, i also have a volant CAI..... last time i did and oil change and fuel filter change was about 4500 miles ago and i always do the same everytime i do service on it. i thought it was the fuel pump but then someone told me these dont have fuel pumps..... anyone know what could be wrong with this truck? its a 04.5 LLY crewcab 2500hd thanks for the help
well my gf woke up this morning and tried to start the truck and it just kept on cranking over and over and over but would not start, so later when i got home i got starting fluid and made it turn on, and once the truck is on it runs perfect. then when its hot the truck turns on and off perfect so im guessing its only at cold start.... i got the obd2 scanner and egr and air fuel module came on, the SEL has been on ever since i installed the 5 inch mbrp exhaust, i also have a volant CAI..... last time i did and oil change and fuel filter change was about 4500 miles ago and i always do the same everytime i do service on it. i thought it was the fuel pump but then someone told me these dont have fuel pumps..... anyone know what could be wrong with this truck? its a 04.5 LLY crewcab 2500hd thanks for the help
If its like my LB7 change the filter, and pump the bleeder up. Try bleeding the system first and make sure there is fuel, my gauge was off and sucked air in, I know the screw and filter are bad about coming loose on the LB7 not sure they are the same or not...
Staging Lane
Joined: Apr 2009
Posts: 76
Likes: 1
From: Ohio, USA
I'd try opening the bleeder on the fuel filter and cranking it to see if fuel comes out. Also try cracking the bleeder and pumping the primer until fuel comes out.
These trucks don't have an aux fuel pump, so troubleshooting is going to be a little different.
The 04.5 trucks had a TSB for one of the injector wiring harnesses...has it been done? That caused our LLY to crap out and not re-start.
What are the codes? The air fuel code could be a symptom of a fuel pressure problem.
These trucks don't have an aux fuel pump, so troubleshooting is going to be a little different.
The 04.5 trucks had a TSB for one of the injector wiring harnesses...has it been done? That caused our LLY to crap out and not re-start.
What are the codes? The air fuel code could be a symptom of a fuel pressure problem.
Staging Lane
Joined: Apr 2009
Posts: 76
Likes: 1
From: Ohio, USA
Also check the fuses and the FICM harness near the alternator. ******** that worked on ours laid the f**king thing against the exhaust manifold, leaving us stranded alongside the road at 3am with a 30ft gooseneck. Turns out it blew one of the fuses when the wires melted and shorted out.
Passenger side wiring harness was an issue with the LLY's. But if it starts with starter fluid then I wouldn't lean that way. Your ECM needs to see at least 8000psi at the rail pressure sensor at cranking. I would look at your rail pressure relief valve. If the truck has alot of miles on it it can be bleeding off at cranking rpm's. after it starts this is not an issue. FCA can also cause this is issue.
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Staging Lane
Joined: Sep 2011
Posts: 96
Likes: 0
From: Littleton, CO
One thing that may sound stupid is make sure the plastic bleeder screw for the fuel filter does not have a crack in it. Happened to my dads. If you drove it around it would start every time. Once it would sit over night it would let just enough air in the line that it would not start with out priming it. Just a thought.
