[40cpe]

The straight-thru part of the tee remains open, one side to the fuel pump, the other to the carb. The remaining side is closed up and drilled small and goes back to the tank. The idea is to have enough restriction in the tank return line to give pressure to the carburetor, yet flow enough to keep the fuel pump pumping cooler fuel. The restriction works like the restriction on the by-pass oil filter.