If you have a DVA that plugs directly into your meter, such as the ones sold commercially, you simply set the meter to the DC VOLTS setting and the appropriate range if applicable. Then, just use your leads to connect in parallel to the circuit as you normally would to read volts.
But, if you suspect it's dropping a cylinder, you may want to use an automotive timing light connected to a 12v. battery to see if you are losing spark on one of the wires.
You can check all the coils with an ohmmeter although I don't have specific specifications for this outboard to give you. Typically, at least
initially, you just want to know if a coil is open (infinite resistance) or shorted to ground (no measurable resistance). The ignition coil, for example, may read: 2 or 3 ohms primary and 20k to 30k ohms secondary.
As far as the charging system (regulator) goes, you won't need to be concerned with that. It has nothing to do with the ignition.
This could be a problem with the CDI box but I wouldn't necessarily suspect that right off. Sadly, I know of no reliable test to see if the CDI is bad other than trying another. I've tried doing the pinout ohms test that Honda lists in some of thier shop manuals but it is confusing and I've never gotten any decipherable results from trying. I'm just not smart enough I guess.
I would more suspect a poor connection somewhere. Taking plug in connectors apart and checking/cleaning pins and sockets is where you could start. These twins vibrate a lot and this action can loosen connections inside the plastic housings. That, or a carelessly reconnected plug can bend pins and distort sockets.
Vibrations can also end up "sawing" a poorly routed wire right in half. Although, once the insulation is rubbed through on a wire the problems will start well before the wire is worn out.
I think looking for corroded ground connections probably makes very good sense in this case. Older outboards will eventually develop corrosion you can't see under screw heads and washers ESPECIALLY where an electrical connection is involved. Taking these connections apart and shining them up as when they were new can often solve a mystery.
If you haven't tried new spark plugs for this concern then that is another easy and cheap thing to try.
Hopefully someone else here has some great suggestions for you.
Good luck.
