QT50 gas leaking out overflow

Bill Switzer /

Gas seeps out of the overflow tube when it's not in use. I tried another needle and seat out of a parts carb that looked in a little better shape than the original, still seeping when it's not in use. I have turned the petcock to the off position, still seeping. Will a bad petcock cause this?

Re: QT50 gas leaking out overflow

If the petcock is off, but gas is still flowing to the carb, then the valve must be bad...

Think about it, the valve is there to stop the fuel from flowing out of the tank. If fuel is flowing through the valve when it is off, then the valve must not be working correctly, right?

Are you SURE that you turned it to 'off', and not to 'reserve'?

Re: QT50 gas leaking out overflow

Bill Switzer /

But I leave the petcock in the on position all the time on one of my other QT50's and gas doesn't seep out of the overflow tube on it. That's why I suspected the needle and seat to be the culprit. Yes, I had it on the off position.

Re: QT50 gas leaking out overflow

Maybe your float is bad?

As far as I know, a bad fuel valve wont cause that... but if your float is stuck open, or the needle or whatever, gas will just keep flowing. Granted, with a moped its not much but its enough.

Check the float and the throttle tension and the spring...

Re: QT50 gas leaking out overflow

You have two problems. The float valve is sticking open - very common. Disassemble the carb and clean with carb cleaner.

Second - unhook fule line and let drain to a glass jar. Turn petcock on and off to see if it is working

Re: QT50 gas leaking out overflow

Bill Switzer /

I haven't tried the glass jar trick, but I've had the carb apart several times. Sprayed the hell out of it with carb cleaner and used compressed air and blew out every nook and cranny in it after each cleaning. The carb is spotless! You could eat off of it! lol.

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