You want to fill the hopper tank first and let it overflow into the main tank. But you need to make sure you clamp off the fuel line from the hopper tank to the carb or you will flood the engine.

Basic setup is this:

Hopper Tank - 3 connections
1 connection from Hopper to carb on engine
1 connection from Hopper to a fill line (make sure you plug this line during engine operation)
1 connection from Hopper tank to main tank

Main Tank - 2 connections
1 connection comming from the Hopper tank into the main tank - (clunk connection)
1 connection from Main tank to tune pipe or fan preasure

When filling you might want to disconnect the tune pipe or fan preasure line so you will not flood the tune pipe or dump fuel into the jet. Just watch the fuel level in the main tank.

JR Gautreaux