First, if you have fuel flowing out of the carb when stopped, you have fuel flowing out when not stopped. L carbs floats are not adjustable. I know it's odd but take my word. You need a new fuel valve. The little part that actually shuts off the fuel that connects to the float. Either that or you need to take off the float bowl and clean the valve to make sure there's nothing in it causing it to not seat properly.
There is no reason you shouldn't be getting close to 50 mpg with a stock carb.
If you fix the shut off valve and your mpg doesn't improve, let me know and I'll give you further instructions.
That is all. At ease.
Edited by Rich_in_Orlando, July 11, 2012 - 04:32 AM.