Power Tune is proprietary engine cleaning product from Mercury Marine, the outboard motor maker. A spray-in engine cleaner, according to Mercury Marine's sales information, Power Tune is "a blend of solvents and oil designed for combustion chamber deposit removal." The process for application is similar to that for using fogging oil when preparing a motor for long-term storage, except that the fuel to carburetor is not shut down -- the motor is shut down manually after you spray the product into the carburetor.
Items you will need
Hose
Flushing attachment
Power tune
Plug wrench
Connect a water hose to the motor's flushing port or a pair of "earmuffs," the flushing attachment that resembles that item of cold weather wear. Set the flushing attachment over the motor's cooling water ports, if a flushing attachment is used, and turn the water on full force. Start the motor and allow it to idle until it reaches its reaches normal operating temperature.
Remove the motor's top cover. Pull up on the "Fast Idle" control. Spray the Power Tune into the carburetor throat. Shut the motor off. Remove the spark plug wires by twisting them and pulling straight up. Remove the spark plugs with a plug wrench.
Spray Power Tune into the plug bores. Allow the Power Tune to remain in place for an hour or more. Turn the flywheel by hand to distribute the Power Tune.
Replace the spark plugs and reconnect the plug wires. Replace the motor cover.