1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 70Get this manual
Ignition Diagnostic Procedures TROUBLESHOOTING TIP: With engine running, use inductive timing light to check spark advance of each cylinder as throttle is opened and closedIf timing advances and retards smoothly on each cylinder, ignition system is MOST LIKELY functioning properly
IMPORTANT: If outboard appears to have an ignition system failure, it is recommended that before beginning in-depth troubleshooting: aCheck ground leads on Timing Protection Module, Capacitor Discharge Modules and ground lead between ignition plate and engine block for proper continuitybDisconnect and reconnect ignition harness connectors to verify proper continuityCORRECTION No SparkTrigger, Stator or Timing Protection Module (TPM) Weak SparkStator Capacitor Discharge Module (CDM)
PROBLEM 1No Spark or Weak Spark on Both Cylinders
2No Spark or Weak Spark on Cylinder