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carbs dumping fuel

cmills2010-08-10 15:28:17 +0000 #1
'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.
Polaris4252010-08-10 15:31:08 +0000 #2
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.
cmills2010-08-10 15:46:23 +0000 #3
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.
Polaris4252010-08-10 16:00:22 +0000 #4
tapped or smacked? haha... it takes a few good smacks...
cmills2010-08-10 17:09:40 +0000 #5
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?
MeanGreenMan2010-08-10 17:28:35 +0000 #6

Originally Posted by cmills

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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