The John Deere L118 is a seated lawn tractor equipped with an 18-inch turning radius and a 42-inch mowing deck. It's been manufactured with a 22-horsepower V-twin overhead-valve engine. Among other highlights are a 2.1-gallon fuel tank, cruise control, and seven mowing positions. At some point, most tractors like these require minor maintenance or troubleshooting to correct minor problems. Troubleshooting can help avoid costly repair bills.
Place the pump hose into the gas tank and start the pump. Each pump has its own set of operating instructions. Fill the lawnmower with new gas and wipe the exterior of the lawnmower clean of any excess fuel that leaks over. Restart the engine. The gas begins to degrade after 45 days of not being used. So if the tractor hasn't been started in months, this could be the primary engine problem. Obey local disposal laws for the old gasoline.
Run the engine for a short period of 10 to 15 minutes to warm the engine oil. Lift the hood and put an oil pan under the drain valve which is located on the side of the engine. Remove the drain valve cap and empty the oil. Remove the dipstick. Replace with clean oil through the dipstick chamber and no higher than the marking on the actual dipstick.
Use a garden hose to apply light pressure to the front grill and radiator, brushing away any loose dirt and debris that could be preventing proper airflow to the radiator and eventually to the engine. Grass and dust can easily build up in and near the radiator fins to affect the tractor's performance.
Lift the hood and locate the spark plug wires. The wires are located on both sides of the engine near the front. They run vertically from the top on the engine down both sides. Pull to disconnect the spark plug wires and remove the spark plug. Replace the spark plugs with new plugs that are gapped at .030 inches. Many spark plugs are sold pre-gapped.
Slow down if the grass appears to be cutting unevenly. Don't assume dull blades are the reason for uneven cutting or blades of grass that were missed by the mower. It could be that you're driving the tractor too fast. If after you slow down and still notice the grass is being cut unevenly, then you usually must balance, sharpen, or even replace the blades.