2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 161Get this manual
500 EFI FUEL SYSTEM FUEL PRESSURE REGULATOR
General Information
The fuel pressure regulator maintains the required operating system pressure of 39 psi 3psiA rubber-fiber diaphragm divides the regulator into two separate sections, the fuel chamber and the pressure regulating chamberThe pressure regulating spring presses against the valve holder (part of the diaphragm), pressing the valve against the valve seatThe combination of atmospheric pressure and regulating spring tension equals the desired operating pressureAny time the fuel pressure against the bottom of the diaphragm exceeds the desired (top) pressure, the valve opens, relieving the excess pressure, returning the excess fuel back to the tank
FUEL INJECTOR
General Information
The fuel injector mounts into the intake manifold, and the fuel rail attaches at the top endReplaceable O-Rings on both ends of the injector prevent external fuel leakage and also insulate it from heat and vibration