Reply to ag-mike:
use red-kote, it ain't gotta be that clean either.
Cleaning gas tanks for years on everything from old one lung motors, to farm tractors, to construction equipment, to fine and rare beautiful antique automobiles I think you wasted your money. Got gum in an old tank, go to the local hardware store and get some lacquer thinner. This will remove the gum. Got rust. go to the local hardware store and get some muriatic acid. Use this only outside, Do not breath it, and have a water hose ready to flush it away. This will remove the rust. Slush it around from time to time for about 20 to 30 minutes. Drain, flush with water. and repeat as necessary until rust is removed. When you are done, blow any excess water away with compressed air to be sure the tank is clean and dry. This is best done on a hot dry day.
Get the tank sealer here.
http://www.enginads.com/pedersen/
I can tell you, this good stuff as i have used it for years with out a problem. Before this stuff was available we used to use formica countertop glue. Problem with that stuff is the alcohol in the gas today will break it down. Friends of mine that have used the red stuff have not had good results in the long run. It is best to let the tank sealer dry for at least two or three weeks with the cap off and holes open before putting any fuel. I know the directions say 48 hours drying time but belive me, a longer time is better or you may be pulling white strings from the fuel tank lines a few days after you put gas in it. Dandy Dave!
Expert, Guns, Women, Alcohol, and Cigars. :yield: