Fuel problems

Replaced the rotor! Drained tank and cleaned and replaced fuel! Idles hard and fine! Finally test drive it and it made it only about a half mile and it shut off ! Tried restarting and nothing first few times then fired up and made it about another half mile then shut off! This time I poured gas directly into carb fired right up ! Then I drove it home and shut it off! I am curious if the electrical fuel pump is not keeping up with the mechanical fuel pump! Place I bought electronic fuel pump had no idea if it was the right size! How can I make sure I get right size efp numbers on old one does not cross reference!