2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 162Get this manual
500 EFI FUEL SYSTEM Fuel Injector Service
Injector problems typically fall into three general categories- electrical, dirtyclogged, or leakageAn electrical problem usually causes the injector to stop functioningNOTE: Do not apply voltage directly to the fuel injector(s)Excessive voltage will burn out the injector(s)Do not ground the injector with the ignition "on"lnjector will openturn on if relay is energizedIf an injector is not operating, it can indicate either bad injector, or wiringelectrical connection problemCheck as follows: Injector leakage is very unlikely, but in rare instances it can be internal (past the tip of the valve needle), or external (weeping around the injector body)The loss of system pressure from the leakage can cause hot restart problems and longer cranking timesInjector problems due to dirt or clogging are unlikely due to the design of the injectors, the high fuel pressure, the use of filters and the detergent additives in the gasolineSymptoms that could be caused by dirtyclogged injectors include rough idle, hesitationstumble during acceleration, or triggering of fault codes related to fuel deliveryInjector clogging is usually caused by buildup of deposits on the director plate, restricting the flow of fuel, resulting in poor spray patternSome contributing factors to injector clogging include; dirty air filters, higher than normal operating temperatures, short operating intervals and dirty, incorrect, or poor quality fuelCleaning of clogged injectors is not recommended; they should be replacedAdditives and higher grades of fuel can be used as preventative measure if clogging has been problem