2010 Polaris Sportsman 850 Service Manual, Page 62Get this manual
ELECTRONIC FUEL INJECTION Fuel PumpFuel Tank Installation
1Reinstall the fuel tank assembly through the right sideBe sure the tabs on the bottom of the fuel tank are sitting in the slots of the support bracketConnect the fuel line to the fuel pump outlet and connect the fuel pump electrical harnessReinstall the vent line to the tank fittingInstall the (2) fuel tank mounting screws and tighten securelyInstall the (4) screws into the bottom portion of the righthand footwellRemove the shop towel from the fuel tank inlet and reinstall the front cab assembly (see Chapter "Front Cab")Connect the fuel fill hose and tighten hose clamp securelyReinstall the front rack or storage box assembly (see Chapter 9)Install the front mud guards (see Chapter "Mud Guards")When the key switch is on, the fuel rail is pressurized, and the EFI relay provides voltage to the injectorsDuring engine operation, the ECU completes the ground circuit, energizing the injectorsThe valve needle in the injector is opened electromagnetically, and the pressure in the fuel rail forces fuel down through the insideThe "director plate" at the tip of the injector contains series of calibrated openings which directs the fuel into the intake port in cone-shaped spray patternThe 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