Polaris Ranger RZR SW, Service Manual, Page: 129 / 346

4.17
ELECTRONIC FUEL INJECTION
4
Middle Rear Gearcase Bolt
Upper Rear Gearcase Bolt
7. Torque the remaining bolt that attaches the bracket to the
front side of the rear gearcase.
Front Rear Gearcase Bolt
NOTE: A multi-directional torque wrench is required
in this application because of the limited access to
this bolt. Check with the manufacturer of your torque
wrench to see if it can be used to tighten left-hand
threaded bolts.
FUEL INJECTORS
Operation Overview
NOTE: All EFI units utilize quick connect fuel lines.
The fuel injectors mount into the cylinder head, and the fuel rail
attaches to them at the top end. O-rings on both ends of the
injector prevent external fuel leaks and also insulate it from heat
and vibration.
When the key switch is on, the fuel rail is pressurized, and the
EFI relay provides voltage to the injectors. During engine
operation, the ECU completes the ground circuit, energizing the
injectors. 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 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 depending on the speed and load
requirements of the engine.
The ECU gathers fuel injection timing information from the
Crankshaft Position Sensor and Camshaft Phase Sensor to allow
for sequential fuel injection.
Fuel
Fuel Rail
Injectors