68 dart gas tank leak

I never got either one of my cars to stop seeping, so being an airplane guy, and along with the gasket, I Pro sealed mine, it's a 2 part fuel tank sealer. Used on seams or you fill in the blank. The part can be separated with a heat gun if necessary. Don't expect to ever have to go in there again in my lifetime.
Unless that car has fuel injection, it should not have a fuel return line?