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SOLVED! Mule 4010 Fuel Injection Idle problems - running rich

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SOLVED! Mule 4010 Fuel Injection Idle problems - running rich

Old 11-06-2018, 08:48 PM
Junior Member
Join Date: Sep 2014
Posts: 6

Originally Posted by locorob View Post
So I finally bit the dust and disconnected the crankcase breather tube on the ol' mule. It started running better almost immediately. It got better the longer it ran and I didn't even clean the throttle body. By the way I did check with the local dealership where I bought it from, they ran the vin number and came up with no recall on the 2012 model throttle body. So here's where I'm at, I routed the breather tube back around behind the fuel rail shortened it so that it turned downwards so I didn't get any water in the crankcase when I washed the engine or drove it thru a large puddle. Now comes the problem, after driving it full throttle down the road the breather tube started to blow oil onto the engine block. So now I'm back to the drawing board, there has got to be a better way to vent the crankcase than back thru the throttle body gumming up the butterfly valves. I thought about going to the local auto parts store and trying to find an old style breather cap that would go over the end of the hose and routing the tube to a different location. Anybody got any ideals? I tried to attach a picture of the current setup but it didn't work. As many people on the forum here with the same problem i figured maybe someone has come up with something I haven't thought of yet.
I am not sure that this is helpful but...

Before I discovered the recall, I disconnected the breather tube, inserted a cheap cloth filter in the open tube opening and taped it facing downward to the frame. I effectively vented the crankcase to the atmosphere (albeit with a filter to minimize my guilty feelings). I plugged the open hole in the throttle body with a rubber radiator plug. I ran this way for a few months without any issues before I had the throttle body replaced. I did wash out the filter a time or two.

Cannot speak to the vacuum issue but can say that I was getting fuel in the oil in the original configuration of routing the crankcase vapors into the throttle body. What a terrible engineering design.

Last edited by Snakebit12; 11-06-2018 at 08:51 PM.
Old 11-07-2018, 01:31 PM
Junior Member
Join Date: Sep 2013
Location: remlap, al
Posts: 4
Default 2012 Kawasaki mule 4010 throttle body

First off, thanks for the responses. I posted pictures in the gallery on my second attempt. I went to O'Reilly 's auto parts and gathered my supplies. I got three feet of 3/8" i.d. Hose, should have been half inch cause it would not go over the nipple on the crankcase so I had to use a short piece of the original hose with a 3/8'' barbed nipple to connect the two. I then routed the hose along the roll cage bar to the left side where I turned it upwards a bit so any oil that entered the breather tube could drain back into the crankcase. On the end of the hose i bought a breather cap from O'Reilly. It's part number elderbrock 43510. It takes another 3/8'' barbed nipple to connect to the hose.

I like the idea that OIIIO suggested with the catch can it would look more professional. I did notice after i started the engine vapors were coming out of the breather cap so i know its venting crankcase pressure without vacuum. My only concern in venting crankcase fumes back into the throttle body by any means is going to lead back to the original problem of the engine running to rich again. Thats just my thought. OIIIO, let me know if you have any luck with the catch can setup. As far as gas in the oil i haven't experienced that yet but I'll keep an eye on it, thanks.

I agree snakebit12 it was a poor design on kawasaki's part.

I posted an update on this topic but it said it had to be reviewed by (a)the moderator before it could be viewed. Maybe it will show up eventually. It didn't turn out well.

Update on my mule. I followed snakebit 's advice and took it to the dealer. They contacted Kawasaki and they agreed to pay for the new breather kit and throttle body. I was out the charge for adjusting the valves. Bumped the compression up from the low 190's to 200 psi. Cost was $110 and a month without the mule. Been driving the fool out of it since and it still runs as good as new. Thanks snakebit12!

Last edited by locorob; 01-24-2019 at 07:13 PM. Reason: Add to post
Old 03-22-2019, 05:12 PM
Junior Member
Join Date: Mar 2019
Posts: 1
Default 2013 4010 Mule idle problems

I have had the same problem with mine. Carried it to dealer three time for it only to not last very long before the idle starts increasing and running rough. When it does this and in Low it is hard to go back to neutral and soot in exhaust pipe . The TB and vent line was upgraded the first trip to dealer. They suggested running a fuel additive but with no cure. I am going to try the disconnecting the crankcase hose and running it to the outside of engine. Thanks for all the insight.
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