The three main components that are needed for your engine to work are fuel, fire, and air. The combustion engine must have fuel so that the engine can fire up. Spark plugs generate sparks via a magnet located on the flywheel and this is what constitutes the fire part of the components, while air is what allows the combustion to take place in the first place. If you are experiencing engine trouble, it is best to have a mechanic professionally analyse it. However, there a few ways to troubleshoot engine problems on your own before seeking professional auto mechanic services.
Inspect the fuel supply
Do this by pulling the fuel line that leads into the engine's carburettor. Loosen the spring clamp that is on it by using a pair of pliers. Crimp the ends together and move it away from the connection at the carburettor. Examine how the fuel flows. It should be flowing freely, and if it is not, then you will have to examine the hose to ensure that there is no blockage. You should also smell the gasoline. The fuel should smell crisp as well as fresh. If it smells stale then you should replace it. Put back the fuel hose then try to start the engine. If it does not start, then your engine may require a professional mechanic to have a look at it.
Inspect the fire component
To inspect the fire component, remove the spark plug and locate a wire that is coated with rubber. This wire attaches the spark plug to the ignition of the engine. Untie the wire. Check the metal part of the sparkplug. If the curved tip is covered in soot and smells like fuel, then the engine had become flooded with fuel. You will have to replace that spark plug with a new one. Before you do that though, you can test the spark plug for a spark. Put the curved part in contact with the metal part of the engine and proceed to pull the cord that starts up the engine. Ensure that you are holding it with the pliers. If it does not emit a spark, a professional auto mechanic will have to replace the condenser.
Inspect the airways
To troubleshoot for air, remove the filter that hides the carburettor. A foam filter will need to be cleaned with hot, soapy water. Ensure that it is completely dry before replacing it. Clean off any debris that might have collected on the top of the carburettor but take pains not to let any particles go down the intake tube. Replace the air filter and start up the engine. If it still does not rev, then enlist the services of an auto mechanic.