Isn't that a fuel syphon?
The fuel tank is a saddle type, it straddles the propshaft, the tank only has one fuel pump on one side of the tank.
The fuel pump sucks fuel from one side of the tank feeds it to the pressure regulator and the excess is fed back to the tank, this is where it enters this piece and as it flows through is draws fuel from the side of the tank without the pump and feeds it into the side with the pump.
The fuel basically is siphoned into the pump side by the return line from the fuel pressure regulator.
At least I think that's what it is!
Stuart