2009 Polaris Sportsman 850 XP EFI EPS Service Manual, Page 56Get this manual
ELECTRONIC FUEL INJECTION Fuel Sender Test
If the fuel gauge reading on the instrument cluster is not working, or if the display reading differs in large comparison to the fuel in the tank, perform resistance test on the fuel senderDisconnect the fuel pumpsending unit connection and measure the resistance between the Purple and Brown wiresIf out of specification, replace the fuel pumptank assemblyPressure Valve
Locate the fuel pressure valve attached to the fuel rail
Fuel Sender Resistance Specifications: Full: Empty: 90 Fuel Pump Test