Primer bulb. The primer bulb draws fuel into the carburetor to make the engine easier to start.
Air filter. If the air filter is clogged or dirty, the engine may not start or may run rough.
Fuel filter. If the fuel filter is clogged, it will restrict the flow of fuel to the carburetor. As a result, the engine may not start.
NGK Spark Plug (BPM8Y). The spark plug ignites the fuel and air mixture in the engine's cylinder to power the engine. If the spark plug is has fouled (if the tip of the spark plug is burnt or damaged), the engine may not start or may run rough.
Fuel tank vent (also called a check valve). The fuel tank vent allows air to re-enter the fuel tank. If the vent is clogged, the engine may stall.