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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyCoupling Bearing Removal
Remove:
Coupling
Grease Seal
Circlip [A]
Special Tool - Inside Circlip Pliers: 57001-143
Remove the bearing [A] by tapping from the wheel side.
Special Tool - Bearing Driver Set [B]: 57001-1129
...
Fuel Hose Inspection (fuel leak, damage, installation condition)
If the motorcycle is not properly handled, the high pressure
inside the fuel line can cause fuel to leak [A] or the
hose to burst. Remove the fuel tank (see Fuel Tank Removal
in the Fuel System (DFI) chapter) and check the
fuel hoses.
Replace the fuel hose if any fraying, cracks [B] or ...
Subthrottle Sensor Output Voltage Inspection
Measure the output voltage at the subthrottle sensor in
the same way as input voltage inspection, note the following.
Disconnect the subthrottle sensor connector and connect
the setting adapter [A] between these connectors.
Special Tool - Throttle Sensor Setting Adapter: 57001
-1538
...