can you clean a fuel tank?

Yes, you can clean a rusted and gunked up tank. My tank was really gross. I first rinsed it out with water, after getting rid of the old fuel first. I put a chain and big bolts inside the tank and bounced it around on trampoline just to break up any loose stuff. I used muriatic acid (hydrochloric acid) to get rid of the rust. Be careful because this stuff is pretty nasty. After rinsing that out, use acetone to clean out all the gas varnish junk. After rinsing, ready to go.
Rod