Fuel Regulator before or after the Carburetor

Thanks, everyone for the help.


I am continuing to have problems with consistent fuel pressure which has been a problem since the Tanks. Inc in-tank fuel pump was installed. The regulator (holley 12-879) is installed before the carburetor.

I need to continually adjust the pressure up and down to 6 psi. The fuel level in the tank seems to affect the pressure. Low fuel level under 1/2 tank equals lower pressure and 3/4 tank and above equals higher pressure.

I am considering adding a second regulator (holley 12-887) to the return line. My theory is to regulate pressure into and out of the carburetor for greater consistency.

Has anyone else experienced this problem or run fuel pressure regulators before and after the carburetor?