Fuel polishing
I have no experience in this myself, but I understand that there are commercial companies who, for a price will drain ALL of the fuel and sediments from your tank, polish the fuel (whatever that means) and return it to a spotless tank. Hmmm, sounds expensive. Last winter, during layup, a friend of mine on an Islander 32 cut a hole in his tank, drained the fuel, scoured the inside of the tank, resealed the tank and replaced the old fuel with fresh fuel. His boat had sat for 4 years, unsold, so he wasn't taking any chances with damaging the engine. I suppose that means it's possible to cut a hole in the tank big enough to reach into the tank and literally wipe it down. He resealed the tank with an aluminum patch and a commercial fuel (not fool) proof sealant, and a lot of sheet metal screws to secure the patch. He has used the boat all summer and not a hint of fuel leaks so far.
