I replied to one similar to this yetserday. Some regualtors are designed for returns & specific pumps... I just ran a return from my reg of my BBC Camaro the other day. A "deadhead" style reulator should not need a return line... but others, if they do not have it, will create excessive pressure to the carb & cause major flooding... if you crack the float bowl nut while it is running, no matter where the floats are set, fuel will puke out @ a rapid rate... causing flooding. Make sure you have the right reg for your pump & know if it requires a return or not. Good luck to you!!