After a year of my 2010 Mule idling terrible and engine dying when I let off the pedal at idle, I finally got serious about fixing the problem.

I read many posts on this and nothing suggested seemed to work.

Repair attempts:

1. Valve adjustment - I read that intake valves could tighten up a bit and cause pressure sensor to misread tricking the system to add fuel at idle causing the rich condition. I adjusted the valves and did find a tight intake valve and loose exhaust valves - but this did not affect idle problems.
2. Spark plug replacement - no change (they were completely black with carbon - but it still ran pretty good).
3. Fuel pump check - remove fuel line from fuel rail and place end into a measuring cup and turn key to "on" and check how much volume you get. Should be more than 1.7 oz. Mine was fine.
4. Fuel injector leaking check - Pulled the injectors and fuel rail, held it all together tightly by hand while assistant turned key to "on". No fuel leaking from injectors. Cranked engine and observed nice spray pattern onto a rag.
5. Throttle body clean - via spraying an entire can of cleaner directly into the throttle body while assistant has accelerator to the floor - seemed to work for 60 seconds and then back to terrible idling and engine died.
6. Last effort before taking it to the dealer: Removed throttle body (PITA), throttle body appeared brand-new inside maybe due to the throttle body cleaning step in #5 above. What I did different was open the electronic servo controlled throttle blade using my finger: full open and full close back and forth - sprayed shaft bearing area with WD40. While fully closed, and with all electrical connections hooked up: have assistant turn key to "on" position and watch the throttle blade - you should see it open slightly. If so - good to go. Put it all back together and start it up. SUCCESS (for me)

Mine idles like new and starts easy.

This is what worked for me. I also read about air temp sensor, but that wasn't my problem.

 

Thanks for the informative post. Glad that you are back up and running.

 

hey, i got a 2012 mule 4010 and when i got it back from the dealer for first service it started idling rough. it got progressively worse over time. i read your post and decided to try what you did before taking it back to the dealer again, cleaning the throttle body was what they were going to do anyway. it worked!!, and it's back to running as smooth as the day i got it. next thing I'll do, and i don't know if it will prevent it in the future, is to run pure gas no ethanol mix in it. thanks for posting you solution it kept me and the mule from being separated for three or four days, don't know if i would have survived!

 

My mule was running fine until I replaced the fuel pump and then the idle became erratic. When I first crank it idles slow but the rpm goes up and down like it wants to die. I reave the engine and let off and it runs idles perfect but when I drive off no matter how fast or slow when I stop the idle is slow again and acts like it wants to die and while stopped I can reave it up and let off and it will run perfect again. Any suggestions on what may be going on? All advice is appreciated.

 

I also have a 2012 Mule that wasn't idling well. I printed off this thread and gave it to a local mechanic but asked him to first check the fuel pump as I discovered bugs in the fuel filter housing on the bottom of the fuel pump. After testing the fuel pressure (which was fine), he noted that there was fuel in the oil - from running rich.

He removed the throttle body (as suggested here), sprayed carb cleaner on both throttle blades, manipulated both blades and re-installed.

Idles like it's new. As an aside, I only use ethanol-free gasoline so I can't blame ethanol.

You guys saved me alot of cash by posting your solution - thank you so much.

John

 

pictures man we need pictures ,, lol

 

No pictures but I do have a video of the repair work...Not sure how to attach it? Edit: The site has a 5 MB limit on file size - my movie is 300 MB.

In any event, this whole issue has become moot from my perspective:

I found that this "cleaning" of the throttle body, while temporarily effective, would last about 6-8 weeks...and then I'd have to do it again. One day, while at my Kawasaki dealer picking up an oil filter, I asked the service manager "What solvent do you recommend for my bi-monthly throttle body cleaning?"

He replied "Why on earth are you cleaning your throttle body every 2 months?". When I explained the issue, he said "There is a RECALL on the throttle body. Bring it in and we'll install a new one...no charge".

When asked why didn't I get a letter on this recall, he responded "Not everyone had problems".

I got a new throttle body and intake and all it cost me was gas money.

My final question was why this problem had happened. He replied "The routing of the crankcase vapors into the throttle body gummed everything up".

So...my advice...if you are having problems, call your dealer about the recall. If not having problems (yet), unplug the crankcase vent hose from the side of the throttle body and plug the exposed port. Just let the crankcase vent to the atmosphere.

 

thanks buddy !!! yesterday I got off in it ,, changed the little fuel tank filter and then just took the intake tube off just aft of the airfilter and revved the motor to full throttle and sprayed gumout till it would almost die then let it come back up to rpm and do it again after about a half a can she was running good ,, but i'll chk out the recall and plug that vent tube ,, thanks for the help mate
bobby allison !!

 

I just purchased a used 2009 Mule 4010 and it has the same idling problem. Does anyone know if there is a recall on throttle body for 2009 Mule 4010?

 

If your question is whether the recall covers a 2009, can't answer....but a dealer can.

I was told that my repair work would have cost $1,700 if not covered by the recall. So be persistent.