Welcome! Hopefully the tank is not full. I am in the same situation. The plan here is to remove the tank, drain the "turpintine" into the tank of a vehicle I'm parting out. Then, the tank will be flushed with mineral spirits and/or lacquer thinner. Remove the sending unit when you do the cleaning, not sure but the chemicals may harm the sender. Probably a good idea to replace the pick-up filter and the gaskets/seals. Good luck and don't get any in your eyes.
