Rust can accumulate on many parts of your car including your exterior, interior, and even your gas tank. Obviously it would be hard to clean your car’s gas tank, but it is possible to clean the gas tank on your motorcycle or moped. Gas forms when your vehicle is stored for often extended periods of times with no gasoline inside of the tank. This allows water to form on the edges and create rust over time.
Clean the inside of your gas tank with a pressure washer if possible. If you can’t pressure wash your tank to remove rust chunks, then degrease it or soak it in hot soapy water. Put the hose over the tank’s outlet and seal it. You can 1 part water and 1 part hydrochloric acid at this point for best results. You can also use vinegar and “The Works” toilet cleaner, each of them contain different acidic levels. Rinse the tank thoroughly with water and cover the inside with layer of baking soda to neutralize the acid. Again rinse with water and let it dry.
Video demonstrates how to remove rust from an old gas tank
For better results you can add an abrasive to your acidic solution and shake it around. Adding nuts and bolts and shaking it around can be highly abrasive but it’s hard to get them out at the end. Another solution is ice chunks from your freezer. They will knock the chunks off the walls as well as melt when you’re done using them. It really depends on how big the whole is to remove your abrasive material from the rusted gas tank.