When using a fuel tank cleaner, first remove the tank and drain all of its fuel, and then clean any accumulated debris or rust that may be present on top of the fuel tank or its assembly. Remove the tank's lock ring, remove its hanger assembly, and flush the tank with high-pressure water mixed with detergent or commercial tank cleaning fluid.
If the fuel tank has debris that has collected on the inside, move the tank in a circular motion while it is filled with water, and empty it out before applying fuel tank cleaning fluid to the inside. Many modern fuel tanks are difficult to clean due to their internal structure, making high-pressure water necessary to reach the entire interior surface.
After the tank has been cleaned, dry it thoroughly by circulating air through the tank or leaving it to rest in a place warm enough for moisture to evaporate. If the tank has an opening wide enough to permit physical cleaning with a lint-free shop towel, doing so is recommended. After cleaning, examine the tank for signs of rust or physical damage; if any is found, the tank needs to be replaced or repaired before it can be installed again.