Polaris 2012 Sportsman Forest 500 International, Service Manual

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4.46
500 EFI FUEL SYSTEM
9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
© Copyright 2011 Polaris Sales Inc.
FUEL PRESSURE REGULATOR
General Information
The fuel pressure regulator maintains the required
operating system pressure of 39 psi ± 3psi. A rubber-fiber
diaphragm divides the regulator into two separate
sections, the fuel chamber and the pressure regulating
chamber. The pressure regulating spring presses against
the valve holder (part of the diaphragm), pressing the
valve against the valve seat. The combination of
atmospheric pressure and regulating spring tension
equals the desired operating pressure. Any 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 Pressure Regulator Test
Refer to the “FUEL PUMP TEST” procedure.
Fuel Pressure Regulator Replacement
The regulator is a sealed, non-serviceable assembly. If it
is faulty, the pump assembly must be replaced. Refer to
the Fuel Pump/Tank Assembly Replacement procedure.
FUEL FILTER
General Information
NOTE: All EFI units utilize quick connect fuel lines.
All EFI Engines use a non-serviceable, high-volume, high-
pressure, 30-micron internal fuel pump filter. The filter is
located inside the tank as part of the fuel pump assembly.
Fuel Filter Service
The in-tank filter is non-serviceable. Tank flushing to
remove sediments may temporarily restore fuel flow, but is
not a recommended service procedure.
FUEL INJECTOR
General Information
The fuel injector mounts into the intake manifold, and the
fuel rail attaches at the top end. Replaceable O-Rings on
both ends of the injector prevent external fuel leakage and
also insulate it from heat and vibration.
When the key switch is on, the fuel rail is pressurized, and
voltage is present at the injector. At the proper instant, the
ECU completes the ground circuit, energizing the injector.
The valve needle in the injector is opened
electromagnetically, and the pressure in the fuel rail forces
fuel down through the inside. The “director plate” at the tip
of the injector contains a series of calibrated openings
which directs the fuel into the intake port in a cone-shaped
spray pattern.
The injector is opened and closed once every other
crankshaft revolution. The total amount of fuel needed for
one firing is injected during each opening. The amount of
fuel injected is controlled by the ECU and determined by
the length of time the valve needle is held open, also
referred to as the “injection duration” or “pulse width”. It
may vary in length from 1.5-8 milliseconds depending on
the speed and load requirements of the engine.
Injector
Injector