What does a spark tester directly assess?

A spark tester is a device specifically designed to evaluate the ignition system in small engines by checking for the presence and quality of the spark produced by the ignition coil. It directly assesses whether sufficient voltage is available for ignition by allowing the technician to see if the spark can jump a specified gap. When the spark tester is connected to the ignition system, it simulates a load while enabling the technician to observe if the spark is strong enough to ignite the air-fuel mixture in the engine's combustion chamber.

The other options are not relevant to what a spark tester measures. Exhaust quality pertains to the emission of gases post-combustion and is evaluated through different testing methods such as using an exhaust gas analyzer. Oil pressure is determined using an oil pressure gauge or sensor that assesses the engine's lubrication system performance. Radiator efficiency involves the cooling system of the engine, typically assessed through temperature readings and coolant flow rather than ignition performance.