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Thread: 2004 Duramax LLY Air in Fuel

  1. #1
    Join Date
    May 2006
    Location
    Castle Rock, CO
    Posts
    2

    Default 2004 Duramax LLY Air in Fuel

    My '04 Silverado Duramax LLY just broke 100K miles. It has been a great truck, but recently started something that has be a bit confused. When I park it with the front higher than the back, even slightly, it gets air into the fuel system and I have to bleed it at the filter housing to start it. If I park it with the front end lower, it starts right up.

    I read several threads here including this one:

    http://www.thedieselpageforums.com/t...uel+filter+air

    I also took it to a shop that specializes in Duramaxes and he told me the same thing. He said that I could replace the filter housing and all would be cured. But he suggested that I install a FASS auxiliary lift pump and NOT replace the housing. I am reluctant to go blow a bunch of coin without knowing for SURE what the problem is.

    Am I on the right track here in terms of the problem and should I replace the housing or just install an auxiliary lift pump?

    Thanks in advance for the help....
    2004 Chevy Silerado 2500HD LT
    LLY Duramax

  2. #2
    Join Date
    Mar 2000
    Location
    Loyal WI US
    Posts
    10,792

    Default

    I would highly recommend the addition of a lift pump although I prefer a quite different setup than waht was suggested to you. Simple, quiet, efficient Kennedy Twin pump setup. If your filter head is leaking it will then leak externally, but I doubt that it will.
    Kennedy Diesel-owner
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  3. #3
    Join Date
    May 2006
    Location
    Castle Rock, CO
    Posts
    2

    Default

    Thanks much - for now it seems to be working. I replaced the filter, WIF sensor, bleed screw and hose clamps. After that, it fired right up, but I just completed it tonight. I like the look of your lift pump, though, and it's priced right.
    2004 Chevy Silerado 2500HD LT
    LLY Duramax

  4. #4
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,382

    Arrow

    If the problem continues, try loosening the fuel filler cap, then run it loose for a few days to see whether a poorly vented cap might be contributing to the problem. A cap that holds too much vacuum (like after an overnight shutdown) could make a minor air leak in the fuel supply system much worse. An air leak still needs to be eliminated, but....

    Jim

  5. #5
    Join Date
    Mar 2014
    Location
    Northern Alberta
    Posts
    2

    Default 04 6.6 duramax running very poorly and a lot smoke

    I have a 2004 6.6 Duramax, LB7,which will barely pull itself. It will not reve over 1800 rpm and there is a lot of light blue almost grey smoke out of the exhaust. On a scope there are no codes and the duration of opening is almost exactly the same for all 8 cylinders. Could alot of air in the fuel cause this problem?
    Would love some opinions.

    Thanks
    Denis

  6. #6
    Join Date
    Mar 2014
    Location
    Northern Alberta
    Posts
    2

    Default re:04 6.6 duramax running very poorly and alot of smoke

    I meant to say no codes and the duration of opening of the injectors is almost exactly the same on all 8 cylinders. The truck has 270k and all 8 injectors were replaced at 200k and then 4 on the left bank were replaced at 243k due to fuel leaking into the crankcase.
    Thanks
    Denis

  7. #7
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,382

    Arrow

    Here's a link to a fairly recent forum thread that discusses how to test for an air leak using a modified cap.

    http://www.thedieselpageforums.com/t...ad.php?t=43065

    Aside from the modified cap, we've been recommending the same procedure since the 1990s. A tightly wrapped oily rag can be effective to seal the air hose well enough to allow testing.

    Jim

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