2009 Yamaha F40 Outboard Service Manual, Page 120Get this manual
Electrical system
2Measure the spark plug cap resistance
Spark plug cap resistance (reference data): 5.0 at 20 (68 F) 3Install the spark plug caps to the spark plug wires by turning the caps clockwisePulser coil output peak voltage: WhiteRed (WR)Black (B) Unloaded Loaded rmin Cranking 1500 3500 DC 5.0 2.7 6.5 9.8
Checking the ignition coil