You may need to do lawn mower repair when your mower is not starting as it should. The four most common lawn problem problems are fuel, air, spark, and timing. Let us try to check the fuel first. Does the gas tank have sufficient gas to make it run? Is the gas an old one? Bear in mind that it is nice to use the old gas from last year for it may affect the performance of your lawn mower. Although in some cases, your lawn mower may start but you won?t always be lucky. You have check if the gas is reaching the cylinder by starting the engine, and if it is not starting properly, you have to immediately remove the spark plug. Several times of unsuccessful attempts in starting the carburettor may result to flooded engine. A flooded engine may affect the ability of your lawn mower to start.