I was wondering what you guys use to remove rust inside tanks?

I have had good success with EvapoRust, here is a recent GT80 that was pretty rusty, soaked in for 24 hours, rinsed a few times with water and coated with some premix to prevent flash rust.

I have had great success with the POR 15 three stage system. It's a bit of work, but well worth it when done. Worth the 50 bucks for peace of mind the tank won't spring a pin hole leak in the middle of the night from rust removal.

Here's my method,
1-degreaser and a lot of bolts and nuts, shake it, repeat as necessary until most is knocked loose.
2-last tank I used Rust-Oleum Rust Dissolver. Sometimes more that one application.
3-after rinse I dry as best in the sun and put in some 90% alcohol to absorb water, blow out with air until completely dry.
No waiting between the steps.

Most guys here have there own methods.
Just don't use Muriatic acid, very toxic and it flashes back to surface rust soon after you rinse it. (I Know)

Make sure you count them !

I submerge the tank in a 5gal bucket of Evaporust if the tank has not been lined, which is the worst thing you can do to a vintage tank IMO as that stuff eventually breaks down and little pieces end up in your fuel system. If the tank has been lined I usually break it down with MEK or Acetone with hardware and a paint shaker. I've cut out the bottom of the tank to remove dents or old liner before and re welded with success.

Great advice! I tried nuts and bolts once and had a heck of a time getting them all back out. It's amazing how they would jam into spots and you'd think you'd be done and then more shaking would result in another rattle... and another... AND ANOTHER...

A cup or two of the small tank gravel along with a cup of kerosene. Seal the openings, shake, rattle and roll. My RT2 tank spent some time, with gravel and kerosene, openings sealed up, in a plastic bag, wrapped in an old blanket, in a box that fit close inside of a dryer and ran about an hour on the tumble cycle. Came out perfectly clean, looked like new. 10+ years later, it still looks like new inside.

I used Evaporust and 100 pennies. Shook it around real good. It worked great.

Home Depot has phosphoric acid, also it’s the same ingredients in Rust-Oleum Rust Dissolver.