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  1. #1

    Default Chevy 7.4 Starts and then Quits

    7.4 had leaking manifold gaskets, so I replaced upper and lower. All was well.

    Then 500 miles later developed a persistent fast idle and vacuum leak.
    Turned out to be a loose lower intake manifold bolt. (Oops)
    When diagnosing the fast idle problem, I went to clean IAC and it came apart, so I replaced it with one from Autozone.

    Now the truck idles great and runs well.
    Problem is when first started it runs for a second and quits.
    Then when restarted it keeps running.
    But when first started it always dies.

    Any suggestions?

  2. #2
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    murdog94's Avatar
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    Take a look at the fuel pressure. without knowing more info. (year, make, model) it is hard to tell you much more.
    Mike

    Currently

    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

  3. #3

    Default

    This is a '96 GMC C3500. Fuel pump and filter are fairly new. It will pull a 32' trailer up the side of a mountain fine,
    but it takes two tries to start it.

  4. #4
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    try getting new IAC, sometimes they could come faulty from parts store, seeing how everything worked before you replaced that i would just return the one you purchased and get new one and try it out
    Stephen- Massachusetts
    2001 Chevy Silverado

    Dear Members, I'm not a certified mechanic i just have a decent knowledge and about 4 years of hands on experience, I'm no way close to a expert but I'm trying to give my best input so bear with my responses please, thanks

  5. #5
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    Alright well i would double check the pressue since the GM pumps are known for crummy well everything. 55-60PSI you must have 58PSI to start. also take a look at the FPR while in there if it is leaking down there is a chance that when you start the first time it dumps the pressure, then holds it on the second try.

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