I have never figured out how the fuel drains from the carb and back to the tank, when the fuel inlet on the carb is higher then the level of the fuel in the float bowl.
It doesn't/can't but people keep saying it.
It can only drain back from the needle/seat but it's impossible for the gas in the carb to be sucked out.
Heat evaporation is what usually empties the bowls.
An electric pump and fuel return line to the tank solves all the vapor lock and drain back issues.
In RRR's case the check valve just keeps the fuel from running back when the engine isn't running.
