2004-2006 Kawasaki 900 STX Jet Ski Service Manual, Page 58Get this manual
FUEL SYSTEM 3-17 CarburetorFuel Pump
Inspect the check valve [A] for damage or deterioration, and replace it if necessaryIf the gasket [B] under the check valve appears damaged, it may leak and must be replaced
Check these rubber parts for damageO-ring [A]
Diaphragm [B] If any of these parts are not in good condition, replace them
the piston diaphragm [A] Checknot invacuumcondition, replace itfor damageIf it is good the vacuum piston moves smoothly in Check that bodyThe surface [B] the piston must not the carburetor of be excessively wornIf the vacuum piston does not move smoothly, or if it is very loose in vacuum piston holder, replace the piston andor the holder