One word of warning - a tank that currently has rust problems will continue to have rust problems until the problem is fixed. Ever notice how quickly rust is attracted to bare metal?
I tried the gravel trick (even strapped it to a cement mixer and let it slosh around for quite some time) but a month later came to a slow stop as the brand new fuel filter clogged up again.
There are products on the market, plus professional services, to de-rust and then seal your tank. Otherwise you'll need to do this next month, next year, or next time you're out in the middle of nowhere late at night on a one lane road in the fog...
-Boyo
