[header] How to clean a gas tank [title] Disconnect the tank. [step] Before doing anything, you need to disconnect the tank from the motorcycle or other machinery. Without disconnecting it, you won't be able to access it or safely clean it. 
Unstrap the tank and unscrew screws or bolts that secure it. [substeps] For lawnmowers and similar items, you'll need to remove the fuel line and spark plugs.