What if you put sugar in the gas tank?

Sugar in the gas tank will not cause the engine to fail because sugar does not dissolve in gas. It will get pulled thru the gas line and into the fuel filter(s) and depending on how much sugar is in the tank, will plug the fuel filter sooner or later. This will cause the car to stall or not stay running. You can either replace the fuel filters until the sugar is gone or get the car to a mechanic and have the gas tank removed and flushed out. This is not a do-it-yourself project. You could also drive the car to the mechanic and then have the fuel filter replaced while they are flushing the gas tank.