[Chuck924]

Picked up my new mule pro mx from dealer last week. Ran it for 4 days, no issues, ran good, very happy with it compared to the 610XC’s I have had previously. Day 5 temperatures were a bit colder, and started running rougher, wouldn’t idle. Finally wouldn’t start at all. Called dealer, said it sounds like plug fouled, maybe I drove it without seatbelt causing it to load up and foul plug ( I told him no, but the. after the call remembered that I did do that...ooops). Said they would pick it up on Tuesday due to the easter holiday.. So Saturday I go out and get a new plug, stick it in, it fires right up and is running good, until Sunday, when it starts loading up again (carbon fouling plug) you could actually smell fuel a little bit. Still ran but wouldn’t idle.

Dealer picked it up Tuesday and called me Tuesday afternoon said they put a new plug in and its running good. I told him that I had replaced the plug over the weekend and it worked for a day before it started fouling out again. He said that the fuel injection is set and thats not the problem ( I dont know crap about fuel injection) Anybody have any ideas? I don’t want to get the thing back and keep going through this, I use it daily here on the farm and its a big inconvenience not having it.


Sorry for the long winded post, but I’m already frustrated

 

[Mule055]

Might try a hotter spark plug... seems to fix the issues on the older mule 610's that fouled plugs

NGK.com: Heat Range Conversion Chart

www.ngk.com

 

[Chuck924]

Might try a hotter spark plug... seems to fix the issues on the older mule 610's that fouled plugs

NGK.com: Heat Range Conversion Chart

www.ngk.com

Thanks for the advice, have had it back for 2 days now and still seems OK., if it starts loading up again I’ll try the next hotter plug.

 

[Jeremy-WI]

I would suspect fuel pressure, oxygen sensor, intake air temp/ coolant temp sensor as a FI system should never run lean or rich if it is functioning properly. The FI system with enrichen the fuel mixture in cold weather similar to using a choke on a carb. I ran my Pro MX in below 0 weather plowing snow and haven't had any issue with it and I bet the rev limiter you hit without the seat belt fastened restricts fuel and shouldn't foul a plug

 

[Zebrafive]

Or the seatbelt "Nanny" may cut the spark?

 

[Chuck924]

I would suspect fuel pressure, oxygen sensor, intake air temp/ coolant temp sensor as a FI system should never run lean or rich if it is functioning properly. The FI system with enrichen the fuel mixture in cold weather similar to using a choke on a carb. I ran my Pro MX in below 0 weather plowing snow and haven't had any issue with it and I bet the rev limiter you hit without the seat belt fastened restricts fuel and shouldn't foul a plug

Thats what I was thinking, something wrong with fuel system , but Allegedly they checked the fuel system and said everything was OK, so I will just have to wait and see. I have bought several mules from a dealer thats 10 minutes away from me, but the family that owned it forever sold the business and the new people cant seem to find any good mechanics, which is why I bought this mule from a new dealer. It doesnt make any sense but I will have to wait and see.

 

[Jeremy-WI]

Or the seatbelt "Nanny" may cut the spark?

I hope not as that would cause big troubles for the catalytic converter