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Merc Carb Adjustment ?

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  • Merc Carb Adjustment ?

    I have a Mercruiser 140 3.0L, 4 Cylinder. With a Merc carb 2 barrel. How do i adjust the carb? I took it out this pastweek to the river. The engine was kind of hard to start. i had to hold the choke flap wide open in order for it to start. When i accelerated the engine would back fire. I have to accelerate slowly in order to get up to speed. How do i adjust the carb? or is it something else? The carb was recently rebuild.
    1984 19' Rinker w/ a Mercruiser 140 ,3.0L , 4 Cylinder

  • #2
    Re: Merc Carb Adjustment ?

    anybody that can help me out? Thanks.
    1984 19' Rinker w/ a Mercruiser 140 ,3.0L , 4 Cylinder


    • #3
      Re: Merc Carb Adjustment ?

      How long has it been since you did a tune-up(spark plugs, wires, cap and rotor)?


      • #4
        Re: Merc Carb Adjustment ?

        I just did it about 1 month ago.
        1984 19' Rinker w/ a Mercruiser 140 ,3.0L , 4 Cylinder


        • #5
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          Re: Merc Carb Adjustment ?

          If you have an electric choke make sure the face plate mark is lined up withthe 1st mark to the right on the choke housing and start from there with the butterfly fully closed (by hand and with throttle cable diconnected) there should be a .080 gap between the throut and the butterlfy if not adjust the accelerator pump rod by tweeking it with plyers. Also make sure that your idle mixture screw is @about 1 1/4 turn out from from being seated. If thats not it check your anti siphon valve and filters. Or you could always go to the stickies adults only @ the top of this forum and download the manual to you engine or use some of the helpfull tips in that section as well. Good lucl!
          1996 Searay 175 Five Series
          3.0LX ser #F553706
          Alpha1Gen2 ser #OF530668
          1998 Chevy1/2 tonW/T
          "faster dad faster" my baby girl in the tube