I'm cleaning out my 28 gas tank again with Evaporust(Rust911 actually which is way cheaper). I tried to start her up a few days ago after letting it sit for 6 months and nothing came out of the gas line. The early 28 roadster pickup is a fresh total restoration about to be put up for sale. I had cleaned the tank out before with Evaporust but got a remote inspection camera and discovered the remaining rust on the roof of the tank. I mixed up 11 gallons of Rust911($60 makes 16 gallons) which is only about $41 instead of 11 x $30 for Evaporust. It works really good and fast. It will also probably still be good after I'm finished. I'll try to keep it filled to the tippy top and check with the inspection camera after a few days. The Rust911 is really a miracle worker for rusty stuff that can be soaked in it. I also revived the glove box hinge on my 36 and the liftgate hinge on my 41 woodie. Can't think of a better way to de-rust either one so easily especially installed on the car. It leaves no residue but dirty black water from the carbon in the rust. Another good think about Rust911 other than being so much cheaper than Evaporust is you can mix it up stronger and then it works faster.
http://28fordarpickup.weebly.com/