Modat22 wrote:

I need to make sure it won't explode and was thinking about letting it
sit in the sun open for a few days then fill it completely with water.

Any other ideas?

It's been years and years, but I remember using the butt end of an Electrolux
vacuum cleaner to blow air into a tank (previously emptied as empty as I could
get it) for about 24 hours. If the tank is sloshable you can try a much less
flammable solvent like paint thinner, which should still dissolve the gasoline,
and then blow *that* out.

GWE