whatever line goes to the clunk goes to the engine the other is the vent line and the tube in the tank should be at the top of the tank and then just left open or connected to the muffler for muffler pressure.since You did not indicate which line goes to the clunk I can not say which goes where.if you choke the carb and spin the prop with out the plug you should see fuel draw to the carb but do not do it alot you will flood the engine with fuel that has to be removed or end up with a hydrulic lock