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Here's one for the carb gurus

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Pugsley, Mar 10, 2001.

  1. Pugsley

    Pugsley 1/2 ton status

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    Here\'s one for the carb gurus

    I've got the typical electric choke Quadrajet, and for reasons unknown, the choke doesn't kick on. I've been fussing with it for three days now, and can't find any reason for it. No choke, no high idle, nothing - Any idea to what could be wrong?
     
  2. prjt_blzr

    prjt_blzr 1/2 ton status

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    Re: Here\'s one for the carb gurus

    Have you checked the wire to the choke for voltage? If that is good then ohm out the choke heater. It should be one of these two.
     
  3. Cavalry

    Cavalry 1/2 ton status

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    Re: Here\'s one for the carb gurus

    If the choke seems to be working electrically, try to rotate the choke, If its loose your adjustment is off and needs to be set. If its tight, pull it out, and check for binding in the linkage. Remember that you might have to maunaly set the throttle to allow the choke to open.


    Luke
    84 K5
    [​IMG]
     
  4. jimmyjack

    jimmyjack 1/2 ton status

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    Re: Here\'s one for the carb gurus

    Another thing to check for is the choke idle setting. If its not adjusted correctly it won't help either. My choke wire was dead for aloooong time and I never knew it.

    creepin' and crawlin'

    Jim
     
  5. Blue85

    Blue85 Troll Premium Member

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    Re: Here\'s one for the carb gurus

    OK, the choke is initially engaged mechanically. It should snap shut on a cold engine with any blip of the throttle. The "electric" part of the choke is really just a heating element. If you disconnect the wire, the choke will stay engaged too long, running it rich on a warm engine. The bimetallic coil in the choke housing supplies the spring force to close the choke when the engine is open and as it warms up, it opens it further and further. So when you first tap the throttle before starting, the choke should spring shut virtually all the way. This is to make it super rich for starting. Then just after the engine starts, vacuum from the carb should pull the rear vacuum break slightly so that the choke opens just a little bit. It will stay in this position until the bimetallic coil is warm enough that it begins to move. Unless, of course you open the throttle. Then, the rear vacuum break should relax and let the choke close some more because you need a really rich mixture when you are accellerating a cold engine. This is because the fuel hits the cold manifold and re-liquifys and less vapor is reaching the cylinders.

    In the process of moving, the choke should be rotating the little lever on the primary throttle shaft to give you high idle. Whatever your problem is, it is probably mechanical. As long as you get 12V to the choke as soon as the engine starts, your electricals are fine.

    Hope that some of this rambling is helpful.

    <font color=green>Stupid tourist at Mammoth Cave, Kentucky: "How many miles of unexplored passages are there?"</font color=green>
     
  6. Pugsley

    Pugsley 1/2 ton status

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    Re: Here\'s one for the carb gurus

    Thanks Guys - It turns out that for some reason, the choke housing loosened considerably, so it had no tension on it.
     

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