AuusiePilot,
My fill up line is underneath the plane also. the carbie line and the pill up line both have clunks on them and arnt twisted in anyways..
It's normal for fuel to come out by gravity and then siphoning of the fill and pressure lines when your lines are below the fuel tank. You must use a stopper to prevent fuel (and muffler pressure) to escape the tank. Check out these [link=http://www.slimlineproducts.com/f1_tank_setup2_1.pdf]instructions[/link] in how to rig different fuel systems for some more information. Good luck on your maiden.