How do you get sand out of a gas tank without ruining the mower? My little one thought it would be a great idea to pour sand into the gas tank of our push mower and I can't figure out how to get the sand out. Is it pretty much gone?

Remove the tank, with it upside down dump it out. While holding it with filler hole down stick a garden hose in and flood wash the tank out. Then blow it dry, rinse with alcohol dump and you are ready to go again. KennyV

To reassure you that no permanent damage could have happened.
It was and is still common to put sand and gravel in fuel tanks when cleaning them for re coating. You put it in and tumble or shake it then flush the rust and scale out ... works great. KennyV