It is important to make sure the fuel mixture on your Johnson outboard motor is set correctly. If the fuel mixture is off, your engine will not run as smoothly or as efficiently as it could. In the short-term this could cost you money in increased fuel consumption. Over the long-term, it may cause damage to the outboard motor resulting in costly repairs or even replacement long before you would normally need to. Adjusting the fuel mixture on your Johnson outboard is a fairly easy process to do.
Start the Johnson outboard motor. Let it idle for a few minutes to warm up.
Remove the engine cowling as per the instructions in your Johnson outboard motor owner's manual. When doing this, you will possibly be exposed to moving parts that are normally enclosed by the engine cowling. Be sure you do not have on a loose shirt or, that you are wearing anything that could become caught in the engine.
Locate the engine carburettor per the owner's manual. Locate the "idle adjustment" screw per the owner's manual. It will likely be at the base of the carburettor, but may vary by engine design.
Turn the screw using a slot screwdriver until the engine reaches a smooth idle, where it is neither sputtering as a result of a lean fuel/air mix or has a strong smell of fuel from the engine running rich. The adjustment is fairly small ranging from a quarter to one full turn only.