After storing your mower for a long winter or if you happened to get some debris in your gas tank, you will want to clean the gas tank out as soon as possible to get your lawn mower running. Debris in your gas tank will clog the fuel line and prevent the carburetor from getting gas, in which case your engine won't run. Cleaning your gas tank takes a few supplies but is well worth it to avoid harming your engine.
Squeeze the clamp holding the hose to the base of the gas tank. Pull the hose off the base of the gas tank. Squeeze the clamp holding the other end of the hose to the side of the carburetor. Pull the hose off the side of carburetor.
Allow the gas to drain out of the gas tank into a bucket. Spray carb cleaner into the hole where the gas line hose attaches to the carburetor, into the gas line hose and inside the gas tank at every angle.
Add 2 cups of gas to the gas tank. Slosh the gas tank back and forth. Allow it to drain into the bucket.
Reattach the gas line hose. Squeeze the clamps, and insert the hose back onto the carburetor and base of the gas tank.
Fill the gas tank with gas.