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Idle missing and hesitation

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by caryhenry, Dec 11, 2002.

  1. caryhenry

    caryhenry Registered Member

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    I need to know how to adjust the idle speed and idle mixture on my stock carb. When the truck is idling, it misses a little in park and when I put it in gear it misses quite a bit. If you gas it at a light, it hesitates a little then goes fine. please let me know what you think my problem may be.
     
  2. Muddytazz

    Muddytazz 1 ton status

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    /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif mine does the same thing...burb is going in on monday to get that fixed /forums/images/graemlins/grin.gif
     
  3. caryhenry

    caryhenry Registered Member

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    please keep me posted on what the problem is.....
     
  4. Muddytazz

    Muddytazz 1 ton status

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    i'll post everything he does /forums/images/graemlins/grin.gif
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    First order of business is how long ago was it tuned up? Plug wires, plugs, cap, rotor all in good condition will make a world of difference compared to only one of those components being in bad shape.

    Don't need to replace the cap/rotor/plugs if they look/spec ok, but plug wires are hard to test. If they are old, replace them.

    If idle is too low you'll need to turn idle up, but if you don't know the idle RPM, adjusting it and idle mix to try and cover up the problem is the wrong approach.
     
  6. caryhenry

    caryhenry Registered Member

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    starting today, when i fire it ups it revs quite high (3000) and hangs out there. I messed with what i thought was the idle, and it made no difference. This things starting to act all crazy.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Sounds like a choke issue if the idle has gone way up when you start it, either that or the throttle is sticking somehwere.
     
  8. caryhenry

    caryhenry Registered Member

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    dorian,
    I checked the chole this evening, and the choke flap is sticking closed whenever I touch the throttle, and is making the engine rev pretty high. What can I do to get it to open up? Do I need to adjust the screw under the electric choke or what?
    Thanks for your help
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Sounds like perhaps the choke itself isn't working correctly. Before you mess with it, watch and see how it's operating when you start the truck up first off. Figure out for SURE what the problem instead of giving in to the urge to try and adjust stuff. If one thing is wrong (such as choke coil) the only thing you do by adjusting other stuff is make it run incorrectly when the real problem is fixed.

    Unless monkeyed with, you have an electric choke, so I'd check to see if thats working correctly. When the truck is running, is the wire to the choke getting 12V. (is it even hooked up to the coil?)
     
  10. caryhenry

    caryhenry Registered Member

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    What happened is this: I was having problems with the idle, so I decided to adjust the fast idle by the choke. After this attempt failed, I realized that a vacuum leak was causing the idle problem(which I immediately fixed). Now, the choke plate is closing and idling the engine quite high. I am not sure how to adjust the fast idle to bring it back down. Please let me know how I should do this...
    Thanks for your help!
     
  11. Ben Malinski

    Ben Malinski Guest

    Fast idle screw is on the passenger side front of the carb. You need a phillips head screwdriver. It's the only phillpips head on the carb below the choke. Screw it out, counterclockwise. I'd wait until the morning when it's cold and been sitting overnight. I've been fussing with mine and now have it down pat!
    Before starting the truck, step on the gas pedal a few times, that puts the throttle on the fast high cam idle. If your choke is working correctly, it'll fire right up and idle high. Remove the air cleaner and turn out the fast idle screw. You need a tach to set it correctly, if not, use your ears. Once you turn out the fast idle screw and it sounds like it's around 900/1000 RPM's, kick the gas pedal so it knocks it off fast idle. Now you need to adjust the "normal" idle. That's on the driver's side. Uses a sloted screw driver. Kind of ackward to get at but you can do it. You need to screw it in or out depending on your carbs needs. You might have the fast idle screwed in so far that it is not allowing the drivers side idle to seat on the screw. Gotta paly with it. Choke? Set it in the middle setting for now if adjust it as needed. You'll see hash marks/dots on the housing on the choke. Find the middle and rotate it and then set the screws. It needs to be cold to set the choke. 1/8th of an inch play. Hope this helps.
     
  12. BigBurban350

    BigBurban350 1/2 ton status

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    Maybe you need a new pump in the carb to correct the heistation. The pump dumps fuel into the carb when you slam on the gas. /forums/images/graemlins/usaflag.gif /forums/images/graemlins/burb.gif
     
  13. caryhenry

    caryhenry Registered Member

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    Thanks man, she's runnin great now! /forums/images/graemlins/laugh.gif
     
  14. RATAH

    RATAH 1/2 ton status

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    So did you replace the choke to fix it?
    im having about the same problem,
     

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