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How do I tune my MerCarb?

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  • How do I tune my MerCarb?

    I have a 1989 Thompson with a 4 cyl. 2bbl. Mercarb. I have had trouble with the engine flooding (gas runs down venturi after engine is stopped, leaves about 1/4" in bottom of intake manifold). I have read some of the postings and am going to check on the float setting, and rebuild the carb while I'm at it. Does anyone know how to tune in the carb when I'm done. There is only one idle screw, but I've never adjusted one before. Any suggestions would be appreciated.

  • #2
    Re: How do I tune my MerCarb?

    You need to rebuild the carb for shure! But you also will need to know which Mercarb you have. Look at this link and measure. The idle adjustment is really easy. Warm engine and then adjust the screw both ways (about 1.5 turns from in) till it idles smooth. Too much either way will (shake). Carb


    • #3
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      Re: How do I tune my MerCarb?

      Thanks,I rebuilt the carb and it runs sweet now. Now I have another post for my stern drive.