I just got this 4 wheeler from my brother and he ran it ragged. No maintenance was done on it. I changed the oil and took it out. It ran great then it started backfiring if I let off the gas too quickly. A friend suggested this could be the sparkplugs. Main issue though- it will turn off when it's running. Usually it doesn't sputter and die, it just shuts off. Normally it will start right back up and start going like there was never an issue. The longer I used it, the more often it would die. So we determined it ran better when the engine was cold. Also, I moved it from NY to Colorado so the elevation is different. I gapped the sparkplugs (which look fine). The air filter is dirty and I am replacing it but I am trying to find out why it keeps shutting off. Any help would be great.

Thanks!

 

Well, lets start with the simple stuff... Do you have a keychain or anything else dangling from the ignition key? On the Polaris they have a tendency to get caught while you're riding and shut off the ignition unexpectedly...

 

No, it's just the key.

 

my 09 850xp did this a few times-

it just plumb stalled on me while sitting idling

It would also stall if I blipped the throttle once or twice quickly while idling...

so I sold it I didn't want to deal with it.

cnc is also correct about the key chain- my 06 800sp would always stall mid throttle in the trails- turned out to be the bottle opener on my key chain- once I removed it, it didn't stall anymore- it would never totally turn the ign to the off position, probably just enough to cut the power

wish I had some answers fer'ya

 

Check the etc slack on the throttle,may need adjusting? On the 850 it's a little different on the other machines,you have to pop the cover and has to have 2mm slack(1/16") on the etc switch contacts inside the throttle housing. Don't know if this will help? Plus see if you can wiggle the wire harness on the T-map and IAC (idle air control) harness and see if it dies or there is a change in idle(intermittent short in wiring harness to the sensors??)Plus there is an inline 20 amp thermal circuit breaker that should be on the harness near the fuse panel that could be cutting off and on if corroded,getting hot, or not making a good contact?? OPT

 

I had the same issue with my 850. It was slack in the throttle cable. easy fix
Good luck