If the surface is corroded or if the blades are damaged, replace the impeller

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblySubthrottle Valve Actuator Inspection
NOTE
Be sure the battery is fully charged.
Remove the air cleaner housing (see Air Cleaner Housing
Removal in the Fuel System (DFI) chapter).
Turn the ignition switch to ON.
Check to see that all the subthrottle valves [A] open and
close smoothly.
Turn the ignition switch to OFF.
I ...
Engine Sprocket Installation
Replace the sprocket washer and axle cotter pin.
Install the engine sprocket onto the output shaft.
Apply molybdenum disulfide oil solution to the threads
and seating surface of the engine sprocket nut.
Tighten:
Torque - Engine Sprocket Nut: 145 N·m (14.8 kgf·m, 107
ft·lb)
NOTE
...
Fuel Tank
The following octane rating gasoline
is recommended for the fuel tank.
Avoid filling the tank in the rain or where
heavy dust is blowing so that the fuel
does not get contaminated.
A. Tank Cap
B. Fuel Tank
C. Top Level
D. Filler Neck
WARNINGGasoline is extremely flammable
an ...