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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyTorque Limiter Removal
Remove:
Starter Motor (see Starter Motor Removal in the Electrical
System chapter)
Throttle Body Assy Holder [A]
Breather Hose [B]
Roll up the heat insulation rubber plate [C].
Remove:
Torque Limiter Cover Bolts [A]
Torque Limiter Cover [B]
Remove:
Torque Limit ...
Fuel Pump Installation
Remove dirt or dust from the fuel pump [A] by lightly applying
compressed air.
Replace the fuel pump gasket with a new one.
Check that the fuel pump terminal [A] and band [B] are in
place.
Apply a non-permanent locking agent to the threads of
the fuel pump bolts.
Tighten the ...
Check 2-1: Speedometer Inspection
Using the suitable stand, raise the rear wheel off the
ground.
Rotate the rear wheel by hand or start the engine.
Check that the display changes speedometer.
If the display function does not work, check the following
parts.
Rear Wheel Rotation Sensor (see Wheel Rotation Sensor
Inspe ...