# carbs dumping fuel



## cmills (Oct 12, 2009)

'07 brute 750. Leaking fuel out of drain tube. Removed carbs, rear carb float wasnt moving like it should-removed and found small spec of sand in fuel jet. I removed this and float moved freely again, and I did check both carbs. Put carbs back on and fired her up, within about 15 seconds the gas started leaking. My choke cables seem to moving like they should but even if they were not, ie "sticking" would that cause the carbs to dump fuel like that? Either way I pulled carbs back off inspected bowls and everything appears to be o.k.. Im just kinda scratching my head now wandering what the heck to do next.


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## Polaris425 (Dec 16, 2004)

Did you spray them w/ cleaner? That will make them stick. Put them back on and run it. If it starts to dump fuel again smack the bottom real good w/ a screwdriver handle a few times.


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## cmills (Oct 12, 2009)

No, I didnt use any cleaner, just blew it out. I tapped on them before I took them off and after I put them back on with no results.


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## Polaris425 (Dec 16, 2004)

tapped or smacked? haha... it takes a few good smacks... :bigok:


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## cmills (Oct 12, 2009)

I read that when the float-valve sticks, whether its trash or whatever that it will eventiually stick again, basically saying that the float-valves would need to be replaced. Any validity to this? Heck, everthing is spotless on the carbs-never drowned out or sucked in mud. I have MIMB snorks and re-jetted, I am kinda suspicious of my K/N filter-if im gettining a good seal. Either way I gotta figure why the carbs are acting up. Is it beer 30 yet?


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## MeanGreenMan (May 24, 2010)

cmills said:


> My choke cables seem to moving like they should but even if they were not, ie "sticking" would that cause the carbs to dump fuel like that?


Yes, it can.
Just checking choke cables is not a sure way. As you may know choke system on BF is not really a choke. But it is a plunger system, like a valve, that opens and closes by the choke lever. And there are two plungers, one for each carb. Choke plunger is made of corrosion and the carb bore where the plugner sits in is made of aluminum. Guess what would happen when there two different metals are rubbing each other?
Corrosion... which is a chemical reaction or transer of electrons from high to low concentration. Every metal has different number of electrons per atom as you learned in your chemistry class. Also, things get worse if you submerge your quad into a mud hole and when a drop of water gets into the plunger/bore area. Water is an excellent electron carrier, in other words, it is conductive. Also, if you use fuel with high ethanol content, it can do the same thing. The ethanol (alcohol) absorbs H2O from ambient air inside the fuel tank and now you have water in fuel. Just like water tends to flow from high to low, electrons do the same thing. With the help of the electron carrier "water", the corrosion is bound to happen. When metals lose electrons, they turn to something else like rust.

Here is the pic of old choke plunger with corrosion.









Here is he pic of new choke plunger.









That's one other reason I love EFI engine whether it is a quad, bike or a lawn mower!


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## cmills (Oct 12, 2009)

I didnt notice any corrosion but I will double check this. Its seems even if there is an issue with the choke plungers that were allowing to much fuel to enter the carb that the floats would "if working properly" close off the fuel coming into the carb? Kinda grasping for straws here, thanks though.


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## cmills (Oct 12, 2009)

The choke plungers are spotless, no corrosion.


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## cmills (Oct 12, 2009)

removed carbs and inspected again, removed floatvalve on front carb, it was all clear. placed carbs level and removed 'T' on drain tubes and filled carbs up with gas.... no leaking. I said screw it and and put the carbs back on and cranked right up with no leaking-so far. Pretty interesting how extremely small particles can cause the float valve to stick. in my estimate i think that K/N filter might not be sealing as good as it should. I also had some gas that made it past the rings into the oil also. Oh well, Ill just ride it and see.


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## rmax (Nov 21, 2009)

mine will leak out the overflow when it gets to around 2 bars left on gauge, fill it up an it quits an will not leak untill it gets low agian


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## cmills (Oct 12, 2009)

Well that was not the end, they still con't to leak so I pulled carbs back off, removed float and float valve's off both carbs. I was told if the tip of the float valve resembled a "hersheys kiss" then it needed to be replaced. It is said that the ethanol in gas will cause a particular wear on the tip of this part. Normal looking float valves will have an exact triangle shape. It seem that such a small discrepancy should not allow so much gas to just flow but it does, ie "a grain of sand will cause similar issues if in the right spot. The tips are made of rubber FYI. These parts are 32 bucks each at Kawi dealer "which is crazy" but at the same dealer I was at they sold a rebuild kit with the 2 float valves and every thing else you need to rebuild your carbs if it comes to that. The kit is from MOOSE products and it was for 70 bucks-go figure. Either way I replaced them two little valves and that was it, problem solved.


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## BleednGreen68 (Apr 19, 2010)

You check float levels? Its probably just yer needles that are bad. We always bench test our carbs before we put them back on the machine. We hook it up to our IV tester. I always buy the original kawi needles. The aftermarket ones are junk sometimes. Probably made in china like everything else in this world.


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