1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 111Get this manual
Troubleshooting Test Equipment
The following equipment is available from various manufacturers to support your ignition and electrical system troubleshootingManufacturer ordering addresses are on the rear inside cover of this manual
5J Spark testers NoS21, S13C, or S48
Peak-reading vbltmeters Mercotronic No781 Stevens NoCO-77 Electro-Specialties NoPRV-1
Stevens Mercotronic No55-4S or 55-6S