Recently my sister was riding it and it started backfiring and shut down on her. She eventually was able to get it restarted, and rode it back to the house where is has since sat for a couple of weeks until I got to look at it.

So first I got on a tried to start it, but with no success. I pulled the spark plug and it smelt of gas, then I placed it against the block and saw no spark the first time. Then I repositioned it and eventually saw a very week and inconsistent spark. Therefore, I pulled the plug to isolate it, and put a screwdriver in the wire cap are retired it. Again a very weak spark and only occasionally. Then after spending an hour pulling the front rack and plastic off, I traced the spark wire to the coil mounted just below the top spotlight on the frame. After talking to a Polaris service guy he suggested to test the voltage at the wires atop the coil with ignition on to see if there is 12 volts there. If there, he said I have a bad coil at $150 replacement. I tested the wire atop the coil with a voltmeter and found the 12 volts with the ignition on, but still no spark. He did not explain what this means only the if I had 12 volts and no spark it was the coil.

I then felt I needed a second opinion, so I called another Polaris service guy from a different location. I described my situation and he immediately said he thought it was the stator at $315 dollar replacement. He said he has serviced Polaris for over five years and has seen a lot more problems with stators then coils. He said the backfiring is because of incorrect firing caused by a bad stator. He said this would also account for the inconsistent firing. He said I could test the stator by checking the ohms of the three yellow wires coming out of the recoil case behind the pull start. He said checking the wiring against a ground I should see open if its good. Then checking the three yellow wires against each other I should see between .6 and .4 ohms if is good. I tested the yellow wires to a ground and found open, so from what he was saying it would be good, Correct? He said if he was a betting man, he would put money on the stator as the source of the problem, from his experience. This guy seemed very informative and helpful, but unfortunately they closed before I could call back with results. He did say he could bench test the coil, but I would have to bring it in, but unfortunately his shop is about 75 miles away.

I’m no mechanic, but know that you need gas and spark for combustion. So here is my question, before I buy a $150 coil not knowing if it’s the real problem does anyone have any suggestions or advice? I hope it is not the stator because its twice as much, but from what he second service guy says its more prone it failure than the coil. Also, does anyone know how they bench test the coils and if so how would I do it with a voltmeter?

I start on this morning at 10 am thinking it was probably just water in the gas, but unfortunately it is not been that simple. I will admit I am a bite discouraged now because I have a small budget for this stuff. This quad has a lot of hours on it, and until now it has been very dependable.

Any advice, comments, or suggestions are very well appreciated. Thanks….

 

Is this a 400 or 500.also did you try a new spark plug ?

 

Sorry about that, I was concentrating so much on getting everything correct on that post that I forgot to include the model. Its a 99' Sportsman 335 4x4....

I am sure its not the plug because I isolated it by sticking the screwdriver in the cap. Moreover, I bought a new NGK anyhow and had the same results, a very weak spark if any at all.

Thanks for the insight....

 

Hi Blade....

I tell ya, I agree with CED. Sounds like it had a fouled plug! Did you start her up with the new NGK, or just look for spark?

I look at it this way Blade....Spark or no spark? You have spark and I look at the isolation test that way because a bad coil or stator in most cases would cause a no spark situation.

What is a weak spark? 30,000 volts? Our eyes may see it as a weak spark but , my eyes see it as SPARK!

Move that spark plug wire away from the cylinder opening and crank her over a few times without the plug in to get excess gas out of cylinder, then try a new plug in her and hopefully you saved up to $470.

" I Tell You What " (Hank Hill)

 

I've had the plug cap come loose from the plug wire ( not come off just loosen up, mine screws into the plug wire) and cause problems. Just something else easy to look at.