bought this to fix fuel drain back problem

Feel free to correct my thoughts, but since this happens to all my carbureted vehicles, I’ve been trying to analyze what happens, and have some questions to consider.

After a hot shutdown, heated Ethanol-tainted fuel boils over and the engine floods. This happens to my cars every time when the weather is warm. If it sits for more than a few minutes, and unless it sits for at least a half-hour, I have to floor the pedal to re-start.

I don’t see a way for the fuel in the bowl to drain back towards the pump, but when the engine and fuel cool, the previously expanded fuel in the bowl drops enough to open the needle valve, which immediately allows fuel in the line to vent while sitting.

Now, if the needle valve remained closed and there was no opening for the vapor to vent, would the fuel in the line and fuel pump continue to evaporate? If not, there should be enough fuel in the line between the pump and the carb to quickly prime the carb. Not an instant start, but much faster than having to crank for 10-15 seconds, which is what mine average.

My ’73 D100 sometimes sits for extended periods and though there are no visible signs of leakage I have seen ¼ tank of fuel evaporate over a couple of months, so if I keep the tank full, Ethanol evaporation is a major issue. If I keep the tank only half-full, evaporation loss is noticeably less. Makes you question how much fuel is actually being saved by adding that crap to good gasoline, and if evaporation is causing more pollution than predicted cleaner combustion is actually saving?