LS1 won't stay running

Discussion in 'Troubleshooting & Diagnosis' started by 81Z28IRSLS1, Apr 20, 2006.

  1. 81Z28IRSLS1

    81Z28IRSLS1 New Member

    3
    0
    Jan 31, 2006
    LOUISVILLE
    I'm installing an '01 LS1 in my '81 Z. It starts but won't stay running. I'm using a Rick's Hot Rod Shop Stainless tank with the GM LS1 fuel pump that they supply. The only codes I'm setting refer to the vapor canister which I have not re-used from the donor at this point. It runs for 2 to five secs. but then quits. I thought I have the anti theft by-passed but maybe not. No theft codes setting. Any suggestions.
     
  2. MikeM79

    MikeM79 Moderator Lifetime Gold Member

    7,022
    0
    Mar 5, 1999
    East Quogue, NY
    Two possibilities come to mind:

    1) You are getting caught by the anti-theft feature. In LS1 engines this needs to be programmed out of the computer, I don't think there is another work around.

    2) The fuel pump is not running after your turn the ignition key to "start". When I start my LS1 car I turn the key to the "run" position and listen for the fuel pump. It will come on and run for 2 or 3 seconds in order to bring the pressure in fuel system up to 58 psi or so. When you turn the key to "start" the fuel pump is then supposed to run continuously until you turn the engine off. I installed a fuel pressure gauge just before the fuel rail. If you did the same then watch the pressure gauge and listen to the fuel pump. If a pressure drop occurs before the engine stalls out then there is your answer. When this happens the engine will not cut off cleanly....it will sputter as the fuel pressure goes away. If it cuts off cleanly then it is probably the anti-theft feature.

    When I did my swap I sent my computer and harness out to be reworked by a pro. The fuel pump is powered via a rather large grey relay that manages the cycle I described earlier. He got rid of the anti-theft feature for me and sent the harness back so that anyone could hook it up and get it running.
     
    Last edited: Apr 20, 2006
  3. 81Z28IRSLS1

    81Z28IRSLS1 New Member

    3
    0
    Jan 31, 2006
    LOUISVILLE
    The fuel pump is running and a volt meter confirmred that its not being shut off. People have said it acts just like an anti-theft car when a non-chipped key is being used. Can you tell me where you sent the PCM for re-programming and the approx. cost?? If I can illiminate that from the formula it will be one less ghost to chase. MANY THANKS MIKE!!
     
  4. MikeM79

    MikeM79 Moderator Lifetime Gold Member

    7,022
    0
    Mar 5, 1999
    East Quogue, NY
    http://www.speartech.com/

    This gentleman did my harness and computer. He is very knowledgeable and is a nice guy also. Dunno what he would charge in your case. A complete harness rework and computer reprogramming runs $750. Not cheap, but it was a genuine "plug and play" deal when I got it back.

    You may be able to find a local guy who knows the "LS1 Edit" software well enough to do this for you.

    Off topic....how are things in "Indianucky" these days? I was stationed at Fort Knox (a long time ago) and remember driving up through Louisville on the Dixie Dieway to get to the clubs in Indiana. Those were the days....LOL.
     
    Last edited: Apr 20, 2006
  5. 3_z28camaro

    3_z28camaro Veteran Member Lifetime Gold Member

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    Dec 17, 2004
    Acton, CA
  6. 81Z28IRSLS1

    81Z28IRSLS1 New Member

    3
    0
    Jan 31, 2006
    LOUISVILLE
    Thanks Mike.
    My volt meter confirms I have fuel pump. People say it sounds just like an anti-theft car when trying to use a non-chipped key. Can you tell me where you sent your PCM for reprogramming and the approximate cost??
    It sounds like the best place to start.
     
  7. burak sozer

    burak sozer Veteran Member

    549
    0
    May 29, 2005
    Eggharbor Twp NJ

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