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2012 gmc issue

Discussion in 'Gearheads' started by Preacherman, Jan 29, 2021.

  1. Preacherman

    Preacherman Sharpshooter

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    My truck will not start when it is cold unless I push the pedal to the floor. However once the engine is warm it starts just fine. It did have a maf code but that has now been fixed. Any suggestions?
     
  2. scott024

    scott024 Sharpshooter

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    It could be the check valve in the fuel pump assembly. Try turning he key on and off a couple times slowly to prime the fuel line and get it pressurized before trying to start.

    I had this issue on a 6.0L Yukon
     
    El Pablo likes this.
  3. El Pablo

    El Pablo Sharpshooter

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    I had the exact same issue and symptoms on my Jeep Wrangler. I just primed it as scott024 mentions. I finally fixed it a few years later when I had to swap out fuel pumps.
     
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  4. Preacherman

    Preacherman Sharpshooter

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    Oops, wrong gear area. Can a mod move it?
     
  5. Preacherman

    Preacherman Sharpshooter

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    I will try to prime it and report back. Thank you
     
  6. KOPBET

    KOPBET Sharpshooter

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    Rent a fuel pressure gauge, free at some auto parts stores.
     
    Last edited: Jan 31, 2021
  7. BReeves

    BReeves Sharpshooter

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    Had a 2000 Chevy PU that did that. After replacing the fuel pump discovered a pin hole leak in whatever that plastic line that runs top to bottom on the pump. It would leak down after it sat overnight but once started it was fine.

    Oh! It is easier to lift one side of the bed than it is to drop the tank. I removed my bed but had the means to pick it up without help. The 2000 only had 6 bolts holding the bed on. Remove the fuel inlet, disconnect the tail light wires, remove the bolts on the driver's side and loosen the bolts on the passenger side. Block up the driver's side, fuel pump is easy from there.
     
    Last edited: Jan 31, 2021
    dennishoddy likes this.
  8. 1911Sooner

    1911Sooner Sharpshooter

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    5.3L ?
     
  9. dlbleak

    dlbleak Super Moderator Staff Member

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    Yessir, I’ll move it to the gearhead section
     
  10. OkdRooster

    OkdRooster Marksman

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    Make Model year, engine, gas, diesel, cng would be helpful.
    on Gas vehicles Pedal all the way to floor usually puts pcm in clear flood mode, which would indicate a flooded or idle air issue.
    Also curious how mass airflow sensor code was “fixed”?
    Does it run and idle ok after it starts when problem is present?
    Note codes not necessarily an indication of a failed part.

    Todays vehicles require equipment and a skilled tech to properly diagnose and repair and guessing at whats the problem usually results in greater expense than paying someone who knows what they are doing to fix it.

    Im suggesting a fuel pressure test and a good scan tool for starters to see all sensor data.
     
    mouthpiece likes this.

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