What is the primary function of a spark tester?

The primary function of a spark tester is to determine if there is sufficient voltage from the spark plug. This tool is crucial for diagnosing ignition system problems in small engines. By simulating the conditions under which a spark plug would operate, the spark tester allows mechanics to observe whether the ignition system is producing a strong enough spark to ignite the air-fuel mixture within the engine's cylinder. A proper spark is essential for engine operation, as it provides the necessary ignition to generate power. If the spark is weak or nonexistent, it indicates a potential issue with components such as the ignition coil, wiring, or the spark plug itself, guiding the technician on where to focus their repair efforts.