fuel line check valve.

[jeepsteve92xj]

Car parts stores seem to not have much for small engines, even the small engine specialty hardware stores don't have extra bit.
From what I read since my original post, there should be one in the fuel pump.
I need to go over all the vacuum lines again, and probably add new hose clamps.
There could be a check valve inside the tank - keeping the line filled is the what we want.
Reading over on Total Ruckus they have electric fuel pumps even on carb'ed motors (controlled by an ECM)

Somewhere I saw a statement that the stock vacuum, or upgrade Mikuni pump actually provide more than enough fuel. Not sure what the output pressure or the pump is, but making sure the carb float and valve are in proper operating order is obviously important.