Consult your vehicle's manual to understand how each part connects to the tank and how the gas tank should be removed.
Make sure there is little to no gas in the car. Drive your car to burn any remaining gas, if necessary.
Remove the tank, based on the instructions in the car's manual. Make sure that your tank is empty.
Fill the tank with fuel tank cleaner, following the instructions on the bottle. In some cases, you will need to dilute the cleaner with 1 or 2 gallons of water. Different cars also take different amounts, so refer to the bottle's instructions for guidance.
Let the cleaner sit for several hours to allow the solution to work on and loosen grime, rust and other deposits attached to the walls of the gas tank.
Clean the tank out with water from a garden hose. Clean the outside of the tank as well.
Repeat the first few steps until nothing comes out of the tank. Rinse the tank a few extra times to be sure that it’s completely clean.
Allow the tank to dry for 24 to 48 hours; be sure your tank is completely dry before reinstalling it. The tank must be completely empty and dry before it is put back on the car.