The tank is pressurized which forces the fuel into the only opening available, the intake tube. There also is a small vacuum which helps this as well. If the fuel supply is extremely low you may get some air into the line. Time your first flight to get a good estimate on flight length then take off a couple of minutes for buffer. Always land before your time runs out. In 30 years, I've only dead sticked because of no fuel 1 time. This WILL work!

P.S. Keep in mind that you'll use more fuel at full throtle than 1/2 throtle. My timing was always made flying an entire flight at near full throtle. (Engine already broken in.)