Welcome Guest - Sign Up today
Welcome Guest - Sign Up today



Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
See more
See less

Merc 50hp Only Firing On 2 Cylinders

  • Filter
  • Time
  • Show
Clear All
new posts

  • Merc 50hp Only Firing On 2 Cylinders

    Hi There
    I Have Recently Bought A Shetland With A 50 Hp Mercury 3 Cylinder. The Engine Starts And Runs Ok But When Put Into Gear The Engine Slowly Dies. Upon Furthere Inspection It Is Only Running On The Bottom 2 Cylinders Loads Of Compresssion Loads Of Spark But Not Running On Top Cylinder. Any Suggestion As To The Set Up With The Carbs, Firing Order Ect Ect Bottom 2 Are Burning Nice And Blue But Only Lite Amount Of Fire In Top Cylinder. Suspect Fuel?????
    And Help Would Be Most Appreciated
    Regards Simon

  • #2
    Re: Merc 50hp Only Firing On 2 Cylinders

    It sounds lean try richening the idle screw on the top carb 1/4 turn and see if that helps about the only other possibility for what you describe would be a bad reed and you don't want to go there.


    • #3
      Sign up today
      Re: Merc 50hp Only Firing On 2 Cylinders

      Have your patner try squeezing the primer bulb, a weak fuel pump will not fill the top carbs and run out of fuel under load.

      If the primer bulb greatly improves it then plan on rebuilding or replacing the fuel pump.