How do you check to see if a coil on plug ignition, like a 5.4 truck is firing a plug, since you can't just clip a timing light around the plug wire anymore?
This is really for a Yamaha Waverunner, that I can't scan (yet).
Use a neon test light like the ones used for testing household electrical circuits. There should be enough electric field to make the neon bulb glow. Try it out by holding it near the spark plug wiring on your car. That will give you some idea of how well or if it will work.
The neon circuit testers have two metal tiped pins that you stick onto whatever electrical circuit you are testing. They are cheap, usually less than $4.