I have a 05 400 with 83 hours on it. It is in pristine condition and has seen mud only once. Which is sad really. Any way, I had a problem where it would cut out and die shortly after it warmed up. It acted like either a fuel problem or a fire problem. I search the internet, including this forum, and found little help. What help I did find came from buckaroo helping someone else out. Anyway, I checked the fuel, fuel lines, fuel filter, emptied the fuel tank, changed the spark plug, changed the ignition coil and pulled my hair out. None of this worked. I dreaded the thought of pulling the cover off of the left side to look at the magneto but knew it was my next step.

I started the machine up and when died I started wiggling the wires that go into the left side cover where the magneto is and it fired up!! Then while it was ideling fine I wiggled the wires again and it died!!!! YEAH!!! I am narrowing it down!! so I pull the magneto cover off the left side of the machine and examine the wires very carefully and found that the wires going into the cover, right where they go in at the rubber part, was chaffed. 3 wires were grounding out on the cover. I had some liquid electrical tape so I put a fix on them. YOU HAVE TO GET A NEW GASKET for the cover, no way to get around it with permatex forma gasket. Bummer.

Long story short, if you are having a similar problem and you have checked every thing else out, start the machine up and wiggle the magneto wires. If it cuts out then you have found your problem. It is an easy fix. Don't be intimidated by having to pull the cover. It is easy to do.


Good luck!!!!!

 

Thank's for the tip joe i'll have to remember this for future use , i have a 2006 AC 400 FIS Auto so far i haven't had a single issue with it ; but you never know when you will need it and i hear you about the mud the last time my 06' 400 saw any mud was the year i bought it !

I only got to ride my 400 on the trail's i like to ride most in April and may 2006 , and the mountain trail's were solid mud with some good water hole's in the Mountain Stream's you could get a run at them and wash the mud off untill you got out of the creek's ; and it turned to mud again !

Man was my Cat muddy when i got back to the parking lot , it was only 2 months old at the time and when i got home i got my pressure washer out and it took me 2 hour's to clean out all of the mud ; but it was worth it all for all the fun i had that day !

2007 was like a dust bowl no water and no mud hole's , i started wearing all white shirt and pant's everytime i rode in 2007 ; and after every ride they were brown and man i hate dust so far it look's like another dry dust bowl of a summer here in North Ga. guess i'll have to go to TN or Alabama to get some mud and water hole's !

Thank's again for the tip and i hope you have a good wet summer where you live , i miss the years when we had the good soaking rain's ; maybe the weather forcaster's will be wrong and we will get the rain we need so bad have fun riding your 400 be safe so you'll be able to ride again another day !.........

 

It sound very similar to the problem that I'm having.
As mine begins to stall, I can hear a clicking sound prior to it shutting off. Was yours doing that?
Sometimes when I run it, I never have a problem at all and it runs great. It's very frustrating