Which one is this? I need to see if my carb is getting gas and I don't know which hose to yank. Please be very descriptive.

 

Remove the air cleaner. The top of the carb has four metal pipes. Two go to banjo bolts, -one above each float bowl. They are brazed to a metal block, to which is brazed a third pipe. This pipe is your fuel inlet pipe.
A seperate pipe, the fourth, is slightly smaller in diameter than the fuel inlet pipe, and is brazed onto a round collar (banjo fitting) which is added last. That's the return fuel line. A central, hollow bolt with a hole in the side of it for regulating carburetor pressure, holds the whole assembly together.

So of the two rubber fuel hoses that are attached to the carby, the fuel inlet line is noticeably larger in diameter. Also, the return line hose has a cylindrical, metal one-way valve in it, whereas the fuel inlet hose does not.

 

Fuel line is the one without the aluminum piece in it, that is the pressure regulator on the return line.

 

The pressure is regulated by the diameter of the orifice in the return line pipe banjo bolt.

 

So what is that aluminum thing... I guess a check valve to not allow fuel BACK on the return..?