1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 123Get this manual
17!1D.R.2.62-.3 STEPIGNITION PLATE OUTPUT TEST
To prevent accidental starting of engine while testing, twist and remove both spark plug leads
1Twist and remove primary leads from ignition coils1]1 2Connect No.1 ignition coil primary lead to Stevens Instrument load adapter NoPL-88 red leadadapter black lead to clean engine groundIf Stevens Instrument NoPL-88 is not available, you can make an adapter using 10 ohm, 10 watt resistor Radio Shack No271-132 or equivalent3Set peak-reading voltmeter to "POS" and "500
04Connect PRY meter red lead to adapter red lead and meter black lead to clean engine ground5Crank engine and observe meter Meter must show 17 volts or higher