You need more than just the owners manual.2007 Polaris Sportsman 800 EFI Service Manual PDF Download
This cheap manual can help on electrical and mechanical repairs along with routine maintenance. Could be the fuel pump as many have had to be replaced over time. One way to tell is with a fuel pressure gauge. Should hold 39 psi+/- 2 psi as the manual calls for. Pumps are cheap if needed.2007 Sportsman 800 fuel pump | eBay
Fuel injection section has the codes and how to check. Sometimes bogus codes may be thrown when another area has problems. Code 51 and 52 are injector codes and usually aren't a problem,but can show up if the fuel pump is bad. Get the manual and take it one step at a time.