1998+ Mercury Mariner 25HP Bigfoot Service Manual, Page 84Get this manual
IGNITION
Recommended Test
(1) (2) (3) (4) PROBLEMCONDITION No Spark Condition (Both Cylinders) Probable Cause Crank Position Sensor Stator (ECM) Stop Circuit Short to Ground:stop circuit leadlanyard stop switchtiller handle stop button (if supplied) d- remote control harness Ignition Coil Primary Circuit Shorted to Ground Spark Plugs Open Ground Condition:ignition coilstator ground(ECM) High Tension Lead Spark Plug Cap (Resistor) Spark Plug Ground Connection at:Ignition Coil Primary LeadsStator(ECM) Primary Coil Supply Leads High Resistance To Ground at:stoplanyard switch (water corrosion) Weak Charge Coil Ignition CoilHigh Tension Lead(s) Spark Plug(s) Spark Plug Cap (Resistor) Spark Plug Cap Leak (ECM) Failure Loss Of Oil PressureOver Heating:timing retards and fluctuates, rpm will drop below 2000 rpm Flywheel Key Sheared (ECM) Unit Perform Test No2 1-2 1-2 1-3 3