If you are trying to keep fuel in the carb bowl, after the car sits for a while . . . don't bother. It is probably more to do with the ethanol blend of todays fuel ! I tried a check valve on my Duster360 - no difference. The ethanol blended fuels evaporate out of the fuel bowl so quick. Then you have to crank and crank to fill the bowl and start the car. I have found switching up to the premium fuel with NO ethanol, keeps fuel in the bowl much much longer ! Sure it is a bit more per fill up, but not having to crank the engine makes a great difference !

Cheers

Mark