Fuel Line Routing ? Need Help
 

I have a 1977 911 that was converted from CIS to Webers. I am in the process of swapping to a Subaru motor and need help to figure out where I stand with the fuel system. I have two lines coming from the tunnel I am assuming are the feed and return lines. From the tunnel one line runs through a Fram FG1 fuel filter. Next the fuel passes through what I assume is an adjustable FPR. from the FPR it runs to a fuel manifold that has two hoses used to supply the carbs, a pressure gauge, and lastly the manifold is connected to the return line. As best I can remember there was no return line from the Webers. The pressure gauge read 4 psi at the manifold that fed the carbs which was placed after the FPR. I know there are pelicans that can explain what is likely ging on with this setup. Please help. Thanks

Webers ned precise fuel pressure at a very low pressure. The only way to deliver this is through a bypass regulator which is what you have. The FPR keeps the supply to the carbs consistent by dumping excess pressure to the return line. Very simple.

From what I can tell from your description, the original setup may have been circulating the fuel pass the carbs (instead of dead-ending the lines at each carb). This is done to keep the fuel supplied to the carbs cooler instead of heat soaking in the lines in the engine bay, waiting to enter the float bowls.

which Subaru motor?

and post a pic of it to show the fuel rails it has