Why isn't gas feeding from the tank?

My ford bronco is a big project. i need the gas to feed from the tank so i can drive it but it wont suck into the lines. no fuel pump yet so dont say that right now im trying to just syphon the gas right from the tank. i only put about 1-2 gallons of gas in it. but when i try to syphon, nothing gets sucked up the tube so i'm thinking that the line that is inside the gas tank might have rotted off or something. any ideas of what i could try?