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Thread: Engine swap issues

  1. #1
    Join Date
    Jul 2013
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    6

    Engine swap issues

    I got a low mileage 5.3 from a 1999 silverado and installed it into my 03 yukon. I swapped the intake, manifolds, oil sender and the install went smooth. But it won't start, it cranks over fine, tested the crank sensor, has good fuel pressure but no spark, any ideas?

  2. #2
    Join Date
    Sep 2005
    Location
    Austin Tx.
    Posts
    13,138
    VATS needs to be turned off.
    1951 3100
    1984 C10

  3. #3
    Join Date
    Jul 2013
    Posts
    6
    Wouldn't the security light be on?

  4. #4
    Join Date
    Sep 2005
    Location
    Austin Tx.
    Posts
    13,138
    This is true.. fuel lines backwards? I did that once
    1951 3100
    1984 C10

  5. #5
    Join Date
    Jul 2013
    Posts
    6
    Quote Originally Posted by ducky View Post
    This is true.. fuel lines backwards? I did that once
    Has fuel pressure, just no spark.

  6. #6
    Join Date
    Mar 2013
    Location
    Long Beach California
    Posts
    637
    i could be wrong but arent the 99-02 computers different than 03+ ??? i cant tell for sure from your post but it seems like all you did was swap the motor only.... if you changed the harness and pcm then nevermind.

    but i also had the same problem when i first tried starting mine. it was a missing ground. yes one single ground wire prevented spark. the one apararantly a lot of people miss. its on the driver side of the block down low. check ALL your grounds as they are VERY important.

    as soon as i connected it, she fired right up. good luck
    Like Tumbler in "Gone in 60" I'll drive anything with wheels or without

    My 95 ECSB LQ9 build thread - http://www.ls1truck.com/forums/lsx-t...to-95-obs.html
    CALI LEGAL ENGINE SWAP!
    Stock 03 LQ9, DBW, 95' 4l80e w/ Transgo shift kit, 2010 50# GM injectors, 2800 Circle D stall, Spectre CAI, Upgraded trans cooler, Home-made E-fans/shroud, Dual EP-381 fuel pumps w/Home-made hotwire kit
    NEXT ON LIST: Dual Battery setup, CAM/Valvetrain upgrade, Build my own rear mount turbo, TRU-TRAC, HIT THE STRIP!!!

  7. #7
    Join Date
    Jul 2013
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    6
    It still has the the original pcm and wiring, all I switched was the engine, not the intake or anything else. I will check that ground.

  8. #8
    Join Date
    Mar 2013
    Location
    Long Beach California
    Posts
    637
    did some more checking, the computers are different but it SEEMS the pcm SHOULD still control it as long as they are both set up for DBC or DBW. but anyway, sounds like its probably that ground. let us know
    Like Tumbler in "Gone in 60" I'll drive anything with wheels or without

    My 95 ECSB LQ9 build thread - http://www.ls1truck.com/forums/lsx-t...to-95-obs.html
    CALI LEGAL ENGINE SWAP!
    Stock 03 LQ9, DBW, 95' 4l80e w/ Transgo shift kit, 2010 50# GM injectors, 2800 Circle D stall, Spectre CAI, Upgraded trans cooler, Home-made E-fans/shroud, Dual EP-381 fuel pumps w/Home-made hotwire kit
    NEXT ON LIST: Dual Battery setup, CAM/Valvetrain upgrade, Build my own rear mount turbo, TRU-TRAC, HIT THE STRIP!!!

  9. #9
    Join Date
    Dec 2007
    Location
    Ponca City
    Posts
    1,606
    As long as u transfer over your old sensors yours will control new engine. Cam sensor can cause that. Double check grounds
    Slowest in Oklahoma...

  10. #10
    Join Date
    Jul 2013
    Posts
    6
    Yep, the small ground on the driver side wasn't on, thanks alot

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