Lawn mower?
I can start my lawn mower but it stops running just as fast as I start it what could be wrong?

Dirty / Old gas is usually the cause. I just had this problem the other day. I took my gas tank off mine, cleaned it and I removed the carb. I found the filters were both clogged so it wasn't getting enough fuel. I used my air chuck to clean them. I put fresh gas in the tank, started the mower and shot a good blast of air down the throat of the carb. It's running like a champ now. Keep the air filter as clean as you can. If it gets too dirty it can cause the fuel to burn rich and that can foul out the spark plug. I use a no foul spark plug... this helps avoid this problem for the most part but remember it needs air, fuel and spark to run. Those are the basics for any combustion engine.