Mallory 4309 Regulator

[sen2two]

I'm helping a friend set up his blow through turbo setup. He has the 4309 Mallory regulator that he wants to install because it is a rising rate regulator. but he is currently running a returnless fuel system. Can the Mallory 4309 be used without a return fuel line?

 

[CarMichael Angelo]

I'm helping a friend set up his blow through turbo setup. He has the 4309 Mallory regulator that he wants to install because it is a rising rate regulator. but he is currently running a returnless fuel system. Can the Mallory 4309 be used without a return fuel line?

Nope.

I'm using the same regulator.

A regulator is one design or the other. A return system is a better system anyway for a street car based on aftermarket availability. The fuel runs cooler, and the pump isn't busting its ass against a restricted orifice the whole time.

Run a return line.