Carb overflowing with fuel. Why?


7 replies to this topic
  • ttr250dude

Posted August 07, 2011 - 01:17 PM

#1

As the title says, gas is coming out of the overflow vent tube. I cleaned everything in the carb very well and it didnt help. I have never messed with the float level setting. I have a big ride coming up tomorrow. Does anyone have any advice?

  • Birdy426

Posted August 07, 2011 - 01:41 PM

#2

two possabilities: 1) the o-ring that sels th removable float needle seat is bad (happens fairly frequently), or the rubber tip of the needle is torn or deformed.

  • LemonDrizzle

Posted August 07, 2011 - 02:16 PM

#3

two possabilities: 1) the o-ring that sels th removable float needle seat is bad (happens fairly frequently), or the rubber tip of the needle is torn or deformed.


Also, there could just be a piece of trash that is stuck to the end of the float needle or there could be a build up of something on the seat itself that didn't come off when you were cleaning it.

  • grayracer513

Posted August 07, 2011 - 07:43 PM

#4

Doesn't happen often anymore, but every now and then a float will "sink", loosing its buoyancy due to a leak. See if both sides float as they should in gas. Also, be certain that the float is assembled correctly and that it moves freely with the bowl on the carb.

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  • atropine

Posted August 07, 2011 - 07:46 PM

#5

also make sure it is truly the overflow tube and not the bowl drain tube. the drain screw came loose on me once and was dumping gas out the drain tube. i assumed it was the overflow tube and it took me a while to figure it out.

  • grayracer513

Posted August 07, 2011 - 08:25 PM

#6

You have a good point regarding the screw, but you should also know that the overflow and drain tube are one and the same. That tube connects to a brass standpipe in the float bowl that limits the fuel level by letting anything higher than the top of the tube run into the open top of the standpipe, down the tube and out. The drain screw closes or opens an intersecting passage that opens to the bottom of the bowl to serve as a drain.

  • Theeebalz

Posted August 07, 2011 - 08:29 PM

#7

i had this on my 250 i just tore the carb off and reset the float and put a new needle seat and valve in it, it ran for a while before the old gas got to the o ring accel pump AND stuck up the pilot jet! *facepalm
pretty much i just gave it a good one over and made sure everything worked and it fixed it. curious but what mods do you run on yours?

  • atropine

Posted August 07, 2011 - 09:23 PM

#8

You have a good point regarding the screw, but you should also know that the overflow and drain tube are one and the same. That tube connects to a brass standpipe in the float bowl that limits the fuel level by letting anything higher than the top of the tube run into the open top of the standpipe, down the tube and out. The drain screw closes or opens an intersecting passage that opens to the bottom of the bowl to serve as a drain.


Thanks Gray; it's been a while since I had that problem and I forgot exactly what the setup in the carb was. Good to know.





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