quadrajet problem?

Discussion in 'The Garage' started by camok5, Mar 11, 2006.

  1. camok5

    camok5 1/2 ton status Premium Member

    Jun 25, 2003
    Likes Received:
    Buellton, Ca
    I am putting a new Sean Murphy q-jet with elec. choke on my buddies blazer and it doesnt want to run right. I put the carb on and when I start it the idle stays at about 1100 rpms, even with the choke disconnected and the idle screw backed off. I have tried adjusting the idle mixture srews and even with them tightened all the way down it still idles high. Also when you shut the truck off it diesels and shoots gas back out of the carb. The carb was built for this engine and should be able to run right out of the box, so what is going on with it? Please help because I dont know how to adjust carbs all that well.
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
    Likes Received:
    Roy WA
    Are the throttle plates closing all the way? I'd disconnect throttle cable at the carb to eliminate that as an issue. Just to make sure it's not holding the throttle shaft away from the adjuster screw.

    Had a Q-jet that would diesel because the throttle kicker malfunctioned and kept it open a hair.

    Take the air cleaner off and check if you can see fuel coming out anywhere odd or dripping/leaking, etc. Don't get too close to the venturi's in case it decides to come back up at your eyebrows. :) Fuel could be getting in somewhere else. (needs fuel to run, if the idle mix screws are tight, where is it coming from?)
  3. R72K5

    R72K5 Banned

    Mar 5, 2001
    Likes Received:
    central IL
    you didnt say anything about the fast idle screw on the pass side of the carb, that cxontacts the fast idle cam part of the choke linkage over there

    did you back it out some ?

    sound slike plates are stuck open, restriction

    do you hvae the right base gasket on it ? not all are the same, even for the Q jets, the plates could be hanging up on the incorrect base gasket, but i am not there to see for sure what the deal is, but this is a real good possibility and very possible, as are a few other things

    ive been through this same deal before, NAPa will fix you up, they have books showing the different Q jet base gaskets and htey keep a bunch of them that they will let you dig through,

    good luck

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