I've got a new 90cc Fuxon mini atv (one of the Chinese imports). I noticed a fuel leak at the tank and replaced the hose which seemed to solve the problem there but it then developed a leak at what appears to be an overflow tube that runs from the bottom of the carburetor down the side of the motor towards the ground. It does not seem to affect how the motor runs. I did try unscrewing the drain screw and retightening. It now seems to be worse and leaks fuel at a rapid rate whether running or not. The motor will die if I plug the hose with my finger. Any ideas? I am thinking that something inside the carburetor is stuck open.

 

In the bowl of the carb there is a hinged float. Where the float hinges there is a needle valve. When the fuel level drops in the bowl, the float drops. This in turn brings the needle down such that fuel flows into the bowl until the float is raised and the needle closes again. Sometimes these needles dont close all the way - either not adjusted correctly, get trash in the way, or just get stuck. The float can get stuck down such the the needle doesnt close too.

I got my daughter a sunl 70 from raceway. After I changed the oil. I lifted the frontend up all the way to tighten the drain plug. When I sat it down it began leaking through the overflow hose as you describe. (It was stuck open). I simply lifted the front of the four wheeler off off the ground and dropped it several times. It quit leaking because the float became freed.

Hope this helps,
Rodney

 

I wish I would have tried that before I took the body off, removed the gas tank, removed the carburetor, tore it down and put it back to gether to fix the problem.

Diagnosis: Stuck pin