How to keep fuel up to the curb after shut off.

The fuel pump comments in post 3 are good. In addition, the carburetor bowl should hold fuel. It can only leak out or boil off. In most carbs, there is no place to leak (I think) unless the bowl is cracked. Fuel is sucked up out of the bowl by aspiration (like an insect sprayer). The Holley 1920 1 bbl has a side bowl w/ cork gasket that can leak. BTW, we don't know what carb or engine you have. A photo would help. Gas leaks would leave a dark residue.