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VOODOO fuel injection

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by tRustyK5, Oct 13, 2000.

  1. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    OK its not my Jimmy (this time) its the wifes Jeep Cherokee [​IMG] but I figured someone might be able to help me out here. And lets face it, you guys are the best out there!!

    Sometimes when I start the grocery getter it will rev to 2500 rpm and then just stay there instead of coming back down to idle. Here's the Voodoo part, if I shut it off and open the hood, wiggle the electrical connectors on top of each injector it will start and run normally!? If I just try and re-start it will do the same thing over and over again until I wiggle the connectors. So what am I actually doing by wiggling the connectors? I was thinking maybe throttle position sensor, but I'm not sure. It will start very weird about 1 in 50 starts, really rough low idle and I think very lean as well (I let it run that way once for a few minutes until the undercoat began to melt[​IMG]). Again this is fixed doing the connector wiggle.
    Anyone with any ideas? I would scan the codes but apparently you need a special tool for these years (88)
    Oh yeah its a 4.0 Liter.

    Rene

    [​IMG]
     
  2. Gandolf

    Gandolf 1/2 ton status

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    It sounds like you may have some corrosion in the electrical connectors. Pull off the ones that you wiggle and do a visual check. If you find corrosion, clean them up with a small brass brush (or emery paper). You can find the brass brush at hardware and autoparts stores. Let us know if this helps. With F.I it could be any number of things, but I would check for corrosion before spending money on new parts. Good Luck.

    '89 K5 Silverado 4" lift w/BFG 33's
     
  3. Depdog

    Depdog 1/2 ton status Author

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    My wifes Ford did the same thing, was the Air Bypass Valve going bad.

    Depdog

    <font color=blue>"Lead, Follow, or BECOME the Trail"</font color=blue>

    http://depdogsk5.coloradok5.com
     
  4. dumbfounded

    dumbfounded 1/2 ton status

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    Sounds to me it may be a seal around the injector or some kind of air leak. If you have an air leak the EFI system will see a lean condition and add more gas > idle increases. Next time try some water or WD-40 something along that nature not carb cleaner that won't slow the motor down. Just use like an old windex bottle with water. You might just spray on the injectors and it may seal an air leak. The injectors have O-rings around the base and if they go bad its like an intake gasket leak and wiggling the connector may be resealing the O-ring..........Just a thought

    Love, Peace, and Hair Grease...........
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Depdog, are the Ford and Jeep injection systems similar? And forgive a stupid question, what is an Air bypass valve?

    Gandolf, I'm going to try your suggestion and dumbfounded's as well. Thanks for all the reponses, I'll let you know what happens.

    Rene

    [​IMG]
     

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