Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 22Get this manual
Out-of-Season Outboard Storage WARNING
As safety precaution, when boat is in storage, remove positive (+) battery cableThis will eliminate possibility of accidental starting of engine and resultant overheating and damage to engine from lack of waterIn preparing an outboard for out-of-season storage, precautions must be considered: 1) The engine must be protected from physical damage and 2) the engine must be protected from rust, corrosion and dirt
2Touch up any paint nicks3Clean outboard thoroughly, including all accessible powerhead parts,
Protecting Internal Engine Components
1Remove the spark plugs and inject small
amount of engine oil inside of each cylinder2Rotate the flywheel manually several times to
distribute the oil in the cylindersReinstall spark plugs3Change the engine oil
Fuel System
IMPORTANT: Gasoline containing alcohol (ethanol or methanol) can cause formation of acid during storage and can damage the fuel systemIf the gasoline being use contains alcohol, it is advisable to drain as much of the remaining gasoline as possible from the fuel tank, remote fuel line, and engine fuel systemFill the fuel system (tank, hoses, fuel pump, and carburetor) with treated (stabilized) fuel to help prevent formation of varnish and gumProceed with following instructions1Portable Fuel Tank Pour the required amount of