Can anyone help ? My 50 hp 3 cylinder 1990 Mercury outboard runs rough, it does'nt appear to be running on the bottom cylinder, <br />It has 2 carbs feeding the 3 cylinders, both carbs seem to be putting fuel in, and there is a spark at all the plugs, but the mixture screw on the bottom carb does'nt seem to alter the engine's when running.<br />I've had both carbs off, they seem ok.<br />When the engines been running and I compare the 3 plugs the bottom one seem clean as though it hasnt done any work, also taking the plug lead off makes little differance on tick over.
