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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyUpper Fairing Assembly Disassembly
Remove:
Upper Fairing Assembly (see Upper Fairing Assembly
Removal)
Headlight (see Headlight Removal/Installation in the
Electrical System chapter)
City Light (LED) (see City Light (LED) Removal/Installation
in the Electrical System chapter)
Remove the screws [A], and separate each ...
Premuffler Chamber Removal
Remove:
Muffler Body (see Muffler Body Removal)
Right Lower Fairing (see Lower Fairing Removal in the
Frame chapter)
Front Seat (see Front Seat Removal in the Frame chapter)
Oxygen Sensor (Equipped Models) (see Oxygen Sensor
Removal (Equipped Models) in the Electrical System
chapter ...
ECU Identification
Most countries have their own regulations, so each ECU
has different characteristic. So, do not confuse ECU with
each other and use only the ECU for your model. Otherwise,
the motorcycle can not clear the regulation.
ECU Identification
ZX1000JB/KB
ZX1000JC /KC
...