1999 Polaris SLH, SLTH, SLX, SLTX, PRO785 Factory Service Manual, Page 132Get this manual
FUEL SYSTEMCARBURETION Fuel Pump Operation Fuel Pump Operation, Keihin
The fuel pump is mounted to the rear cylinder (PTO end) carburetor on the SLH and SLTHThe pump supplies fuel to both carburetorsOn three cylinder models (SLX and SLTX) two fuel pumps supply fuel to each of the end carburetors and commonly to the center cylinderWhen the piston is on the upstroke crankcase pressure is low, the diaphragm in the fuel chamber moves outward toward the chamber coverThis causes negative (low) pressure in the fuel chamberThe check valve on the fuel supply side of the chamber opens, allowing fuel to enterThis vacuum causes the outlet check valve to close so fuel cannot return from the carburetorSee III1III1 Piston on upstroke Inlet check Outlet check valve closed