Pump it out with a hand pump.
bad fuel sensor in the gas tank.
YOU HAVE TO DROP AND DRAIN THE TANK
leak
Bad fuel fill.
The fuel sensor in the gas tank is bad and needs replaced.
get it all out empty the fuel tank put good gas in the tank and crank it until it starts
Add 1 bottle of ordinary rubbing alcohol to the tank. If The Bad gas is just gas that has water in it, then the alcohol will allow the water to "burn" with the gas. == == The best way to do it is kind of a pain. Take the tank off and dump the bad gas out. While the tanks off would be a good time to flush it out too. You can use a ordinary garden hose and siphone the gas out of the tank.
bad things
Depends on how you get it out. If possible the tank should be drained and the lines disconected and flushed. If you can drain or syphon the tank on a modern fuel injected car the system should circulate the bad gas back to the tank in just a minute or two when trying to start the car. REMEMBER this will not work unless the tank has new good gas in it. The amount of bad gas in the lines should not hurt the new gas as long as you have a Half tank or more of new gas.
A bad sending unit in the gas tank.
Bad fuel level sensor.
The sending unit in the gas tank is bad.