# 2010 brute force EFI smoking, misfire, oil in air filter area



## redrancher05 (Nov 2, 2009)

I will try to be as thorough as possible and will follow through with the solution so others can learn from this. 

So.... I purchased a used 2010 brute force 750 efi with around 350 hrs that was stated as needing a fuel pump. I went to look at it and it would not run. It turns out the wire harness has been messed with and sloppy repairs made. It had a hard wired fan, the front 4x4 actuator was removed. *currently the 4x4 2x4 light flashes on the dash. 

At first the efi light would flash. I pulled the fuel pump, it was an amazon aftermarket pump. After looking closer there was a bad connection. Put back together, can hear it run when I turn the key on. Bike starts right up and idles smooth, no more efi light. 

This is where it gets interesting. Idles nice, then I took it out for a test drive. Barely goes 20mph wide open. I look back and thick smoke follows. Drive home, pull air box and oil is everywhere. I clean it up and with the filter off I start the engine. Idles great. Then I add throttle, still good, add more, the back port starts to pop occasionally and I can tell the engine is losing power. The front port seems fine. 

The crankcase vent seems to be sending out a good amount of air but does not expel oil at idle that I can see. 

Ok, out driving it's leeks ok up to 1/4 throttle. Flooring it results in pops sputtering and bogging. I put my hand over the end of the snorkel and it seems to pull harder and rev higher but it blows out THICK black smoke when I do it. Is it in some sort of a limp mode? Again, aside from the 4x4 flashing everything else is good.

I am at a loss. Is it the fuel pump really? Why only the back cyl? New plugs were installed. Thank you in advance.


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## redrancher05 (Nov 2, 2009)

Any help would be greatly appreciated. I have searched and searched and cannot find a solution.


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## NMKawierider (Apr 11, 2009)

It's been screwed with too much for us to help much. Parts missing, wiring mods, aftermarket pump, crankcase vent discharging lots when it shouldn't...ect. Best take it in.


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## wideawakejake (Sep 29, 2012)

you said it has snorkels, does it have an aftermarket CDI box? have you pulled the plugs and looked at them? also, you might want to pull a pvc snorkel section or two off and inspect the insides. could show you signs of water abuse(sinking).


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## Dkh100 (May 20, 2014)

Sounds like the air box is making a vacuum causing oil from the case to be sucked into the air box . Is there any other way he's got the snorkels set up to suck air into the box a different way ? I know some people do the duel air box mod . Or the catch box mod


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## redrancher05 (Nov 2, 2009)

Thanks everyone. It is frustrating but I am going to fix this on my own. I will be looking and trying to correct the wiring tomorrow. I have pulled the plastics and taken apart the snorkels. No mud inside or water signs. When I pulled the plugs the front seemed normal, the back was a bit black. I put in new plugs after that. I think there is a wiring issue. I will dig some more and post what I find. Thanks.


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## redrancher05 (Nov 2, 2009)

Wiring is sorted out. The only issue is the 2wd 4wd light flashing. This would not cause limp mode would it? It will not rev very high, idles great but misses and pops then starts to smoke. I try to drive it and it will barely pull itself.. Does this sound like a valve or valve seal? I partially cover the intake and it revs but smokes badly.


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## redrancher05 (Nov 2, 2009)

I pulled the fuel line(efi) and turned it on, fuel dribbled out. . As I understand it there should be 45 or so psi. It should blast out right?


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## dman66 (Feb 20, 2011)

Your correct , the fuel should not dribble out . Check fuel screens on the tank inlet and at the fuel petcock .


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## redrancher05 (Nov 2, 2009)

Will do.


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## redrancher05 (Nov 2, 2009)

Fixed. The smoking was oil being sucked into the air box from a lean condition. It was the upper hidden fuel filter (mesh). Ripped the mesh, purchased efi fuel line and added a filter. No smoking and runs perfect. Love the forum.

---------- Post added at 11:15 PM ---------- Previous post was at 11:12 PM ----------

Another thing. The pressure was there but the volume was not. Mesh was inhibiting the volume needed.


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## brute750outthe910 (May 6, 2015)

i have some of the same things wrong with my bike and I'm gonna be thorough as possible. i rode my brute all day cut it off. next day went to ride and had to hold the gas to crank it. then it would barely pull itself and after 1/2 throttle it smokes and is now leaking oil from the rear exhaust port. please help!!


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