A couple of suggestions, in addition to vapor lock addressed by Paul;
1) Be sure you have a vented gas cap.
2) You may have sediment in your gas tank. Heavy scale will plug the fuel outlet from the tank. Or you may have an in line fuel filter that is full of sediment and needs changing.

Good luck and let us know how you are doing,
Kent

1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix