Honda WB20XT Owner's Manual page 27

OPERATION
3. Turn the fuel valve lever to the OFF position.
FUEL VALVE LEVER
OFF
After use, remove the pump drain plug (see page 41), and drain the
pump chamber. Remove the filler cap, and flush the pump chamber
with clean, fresh water. Allow the water to drain from the pump
chamber, and then reinstall the filler cap and drain plug.
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