Larry,
If you are referring to the white translucent tube, it is there as an overflow and indicator if the diaphragm develops a leak. You will see blue fuel stains in it if your pump is leaking. It just goes down in the tunnel behind the nose gear behind the brace that runs across the tunnel opening. Mine exits pretty close to the breather tube opening.
Building a 14A with a 390 Lycoming
Would anyone know where the small tube off the mechanical fuel pump goes? Would you have pictures or where I can find it in the plans.
Thanks! Larry