Been Around the Block
I recently read here or on another site of a way to clean rust from within a gas tank for $30.00 and does not require coating. It is very simple to the point of being unbelievable but it WORKS!!!! First buy a large box of 1" long sheetrock screws, $20.00. Then buy 4 gal's of white vinegar from the grocery store, $10.00. Then simply insert all the sheetrock screws into the tank, close the cap and shake the hell out of it by hand. I shook it on and off for a day. Every time I walked past it I would shake it. This process knocks off all the loose rust within the tank. I removed the screws. Then simply filled the talk to the brim with vinegar and closed the cap. I let it set for two days. I then poured out all but approx. 1/2 gallon of vinegar. I then added the sheetrock screws again and shook the hell out of it again. Removed the screws again and refilled the tank with the same used vinegar. Let it set another day. Drained the vinegar out and flushed the tank out with a water hose. After flushing it out, I immediately poured Coca-Cola into the tank and sloshed it around good to keep it from flash rusting. It was that simple. It took it down to bare matal......... Mine looked so good after that I didn't even have to coat it inside. The first picture below is of the large pile of finely powered rust dust that came out of the tank when I emptied the screws out.