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Quadrajet Part

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mikeyg79, Oct 20, 2002.

  1. Mikeyg79

    Mikeyg79 Registered Member

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    I have been trying to find out what this part does on my '84 quadrajet and was wondering if anyone here can tell me what it does..
    I thought it had sometinhg to do with the fast idle, but when removed, the truck still idles fast when cold.
    [​IMG]
    [​IMG]

    Thanks
    Mikey
     
  2. Great78burb

    Great78burb Registered Member

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    I'm pretty sure that it's used to raise the idle just a hair when the a/c is turned on. Do you have a/c, or did you originally? The fast idle is part of your choke. /forums/images/graemlins/burb.gif
     
  3. Mikeyg79

    Mikeyg79 Registered Member

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    No ac, no power anything, just a plain old 84' Custom Delux K20.

    Mikey
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    I believe thats an anti diesel solenoid or its a deceleration solenoid. (friends C30 has one) Too early to be a power steering kicker I think.

    Either way its designed to kick the idle up. If its not in contact with the throttle linkage (and its not in those pictures) then its not affecting idle obviously. I'd just leave it if it doesn't make any difference hooked up or not.
     
  5. Mikeyg79

    Mikeyg79 Registered Member

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    Well when my truck is just starting and cold, the plunger comes out and hits the throttle linkage.
    The bad part is it doesn't always stay retracted- even when the truck is warm.

    Mikey
     
  6. wrathORC

    wrathORC 1/2 ton status

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    Is it the original carburetor?

    Are there any wires hooked to it?

    What does it press on? If it were to extend what does it do?

    Does that vacuum line go to a switch? If it goes to a switch use a test light to see if it energizes when the defrosters or AC is on. If you don't have AC and never did then scrap that. Then use the test light to see if the switch is energized when the truck is running versus when it is in the "ON" position but not running and also in the "OFF" position.

    What are we looking for? Well, back in the day when GM had some freaking crazy emissions crap they had a problem with dieseling when motors were hot (87 octane gas, high compression, and a 195 thermostat makes heptane ignite without much effort) so they used a system that completely closed the throttle so it'd be less likely to diesel.


    Also, back in the day, farmers used to have little solenoids that bumped up the idle when using PTO accessories. My Dad said years ago that he only saw them on big blocks though. Do you have PTO?

    It looks like you still have the AIR pump on there, you really need to get rid of that POS.
     
  7. Mikeyg79

    Mikeyg79 Registered Member

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    There is no AC, no PTO, no power accessories other then PS.
    If the plunger extendes it hits the throttle linkage (only enought to bump the throttle up a bit.) It does not completely close the throttle.
    I thought it was the fast idle, but it still idles fast without this.
    There is a vacuum line from the base of the carb to a switch with 2 wires off it and another line from that to this device.

    Mikey
     
  8. 77fixer

    77fixer 1/2 ton status

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    I believe it is a piece of emmision crap. It slowly releases the throttle even if you lift your foot suddenly. Closing the throttle quickly when decelerating somehow increased emmisions so they added that piece to prevent that from happening.

    Brett /forums/images/graemlins/burb.gif
     
  9. wrathORC

    wrathORC 1/2 ton status

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    Find out when the switch is on and when the switch is off. It's there for a reason, even if it is a crappy one.
     

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