40 Merc

Discussion in 'Bubba's Outboards' started by Poppa, Aug 28, 2008.

  1. Poppa

    Poppa New Member

    Messages:
    1,233
    State:
    Pinson, Al
    I have a 40 HP mercury that had set up four years. The carbs were gummed up and I disassembled them and cleaned them with carb cleaner and blowed
    all the orffices with air. The motor runs good and I have no trouble starting
    but it seems to be running a little rich and will not run at a slow idle for
    very long. It is a 1994 inline 4cyl. It has 2 carbs and the carb have only one
    adjustment screw. I think it needs just a little twiking but I don't know the
    best way to adjust the carbs. Any suggestions will be appreciated. Thanks
     
  2. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Ward you have to adjust those while in the water and in gear. If after setting and it still won't idle at low then its cleaning the carbs again or a coil breaking down. You turn those screws out from a gentle bottom seat about 1 to 1,1/2 turn You let it warm up firs and real good set both screws all the way in and gentle seat them and back each one out 1 to 1.1/2 turn Start the engine put it in gear and back a screw out one at a time until it starts to miss then wit about 10 seconds and let the motor collects itself and turn that screw back in about 1/8 turn or until it quits missing now keep in mind you want to do this in 1/8 increments and wait for a few seconds to let the carb corrects itself to the adjustments. after doing both carbs then if it bogs on take off one is set to rich you need to screw one of them back in until you get the bog out. All this has to be done on the water and while in gear or it won't work.