i was riding yesterday and all of a sudden it started back firing out the exhaust and i think its running lean cuz the exhaust pipe got so dang hot that it burned my leg and started melting my plastics !it runs fine under hard accelaration but with 1/4 throttle its spitting & sputtering backfiring like crazy but when i give it more throttle it clears up and runs fine til i let out of throttle and it back fires again and also it idles fine and no check engine light on either ! someone plz help im bout fed up with this machine !!!!!!! thanks

 

It could be an exhaust leak, with efi it should adapt to how much gas to let through so it shouldn't run lean, check, and make sure no air is escaping when you give it gas

 

yea but shouldnt i be able to hear if it had a exhaust leak ?

 

I have a polaris outlaw and I got an hmf for it and rejeted it, I would ride and let off the gas and I would get a bunch of little pops. Then I felt up by where the header comes out of the engine and it was a pretty bad leak, you could feel the air coming out. Or it could be leaking where the header hooks to the slip on.

 

On some of the early 700 and 800 efi machines we had to reflash them because of running too lean. Had some that the pipes would glow cherry red. This usually took care of the problem. But like suggested I'd check for any exhaust leaks too. Plus not a bad idea to check out the " sticky" post on efi problems above this section.A sensor harness short could cause problems also.

 

Ok I think I found my problem , there's a pin hole in the engine intake hose coming from throttle body !

 

Oh and one more question , could I had damaged my motor by running lean like that ?

 

You could see if that solves the problem just by plugging up the pin hole with tape. If it doesn't help then the problem is else where. Only so much you can do on efi machines without hooking them up on Digital Wrench at a dealer to help narrow down any harness or fuel delivery problem. Yes to answer your question, if they run lean for an extended period of time you can burn a hole in a piston,seize rings,etc.