Small Engines (Lawn Mowers, etc.): Scotts lawnmower 6.0, fuel tank cap, grass catcher

Question
The gas tank on my lawn mower is leaking about an inch down from the top. What can I do to fix it myself? Also the mower has been starting and running really well. I tried to start it three days ago and it wouldn't start. I replaced the spark plug because it was dirty. It sparks but still won't run. You are supossed to prime three times but it still doesn't start. The serial # is 2285JOX8A. It is the mulcher/mower model with the grass catcher.

Answer
juanita
Here are some helpful tips.

Problem: Engine will not start or is hard to start.
Possible causes:

Fuel tank is empty or shutoff valve is closed, or fuel line or fuel tank cap vent is clogged.
There is water in the fuel.
Carburetor is overchoked.
Carburetor is improperly adjusted or needs service.
Ignition system or its wiring is defective or ignition switch is off.
Deadman or other cutoff switch is open or defective.
Spark plug is fouled, improperly gapped, or damaged.
Engine compression is poor