2007-2009 Yamaha F15/F20 Outboard Service Manual, Page 254Get this manual
Starting systemIgnition and ignition control system NOTE: To prevent the engine from starting when cranking it, be sure to disconnect both spark plug caps2Connect the spark plug cap to the special service toolS6AG8030
Spark checker: YM-34487 3Crank the engine and check for sparkIf there is no spark, check the ignition system2Measure the spark plug cap resistanceReplace if out of specification
S6AG8040
S6AG8020
Spark plug cap resistance: 3.756.25 k
WARNING
Do not touch any of the connections of the special service tool Be sure to install the special service tool to the spark plug cap so that sparks do not leak out Keep flammable gas or liquids away, since this test can produce sparksNOTE: Repeat steps 23 for each spark plug cap