2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 222Get this manual
TRBL SHTG
Troubleshooting
Symptom: Engine cranks, but will not start (engine stop lanyard switch is operating normally) Check the ignition system Check the fuel system Check the compression pressure of the power unitCheck that the spark plugs produce sparks
WARNING
Do not touch any of the connections of the spark checker leads Do not let sparks leak out of the removed spark plug caps Keep flammable gas or liquids away, since this test can produce sparksCheck the ignition spark using the spark checkerCheck the ignition system output peak voltage