I have a 2008 Polaris Sportsman 800. About a month ago, I was out on the trails and had went about 12 miles running at a good pace with no troubles at all. We stopped to take a break for about 15-20 minutes. When I went to start the quad, it started to backfire and sputter really bad at idle. After a few turns of the key switch (maybe 3-4 times), it was back to normal and ran great until our next break. This happened all day off and on. I did fill up with regular octane gasoline like I always do.

One week later, again at the start of the day, no problems!! Then it happened again. But my buddy thought that it might be in the injectors so he took off like a bat out of he11 and opened up a bit. ( most of my riding is under 25 mph). It seemed to work but just for a moment.

Third week, getting worse. The quad runs great when it started up but causally throughout the weekend the sputtering was worse and more often. Keep in mind, this only happens after I turn it off from a longer run.

Now, even more worse. Now its happening when I start it for the first time. It still goes away after many turns of the off/on key switch and when it finally runs right.............its mean.

Any suggestions on what to look for? I have two weeks to tear it down and fix the problem before our annual night run. I plan on a complete tune-up with changing all the fluids and filters but I don't think this is a normal maintenance problem.

 

Look at the "sticky" post in the expert section on 700 and 800 efi electrical problems. The most problems we had were on the t bap(map) sensor harness and connectors. It will cause erratic running,sometimes good,then all of a sudden runs crappy. Stronger OTB brand harness kits are available. Only The Best You can check for any bare wires running from the sensors or any soft wires meaning internal breakage.Also to eliminate a fuel pump as an issue ,if you have a fuel pressure gauge and adapter for the fuel rail,the pump must hold 39 psi with out any drop when the key is turned on and the pump primed up.

 

Okay,
1) ran the codes and both 41 and 45 showed up!
2) I didn't find anything disconnected but I did find exposed wires...see below
3) Is this what is causing the problem?
4) best solution to fix it?

 

Codes show tbap problem. Found a bunch like this. Some would just have bare wires,some melted inside,plus the connectors are junk. Order the OTB harness like a bunch of people have been doing. Polaris repair kits are the same thing you're holding.

 

OTB harness on its way. I hope these are easy to install. Im a weekend mechanic at best.

 

Should be like the Polaris kits with shrink connectors and instructions.