Mercury - Ignition Timing

Outboard Motors
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Ignition Timing

IMPORTANT: If “TDC” mark on flywheel is not in alignment with crankcase cover/cylinder block split line, check for (and correct) one or more of the following possible causes.
TDC Timing Mark Alignment
IMPORTANT: As this ignition system utilizes electronic spark advance, no adjustment to ignition timing is possible. If ignition timing is not within specifications, refer to “Test Procedures” following to locate faulty component(s).
a. Dial indicator has been improperly set up or misread.
b. Flywheel key is sheared.
c. Flywheel is installed incorrectly.
4. Remove dial indicator and adaptors.
1. Remove spark plug.
2. Install dial indicator through spark plug opening in cylinder head.
5. Install spark plug and connect high tension spark plug lead.
Checking Timing
1. Connect timing light (91-99379) to engine.
2. Start engine and allow it to warm up to normal operating temperature.
3. Throttle engine back to idle and shift into “Forward”
4. With engine idling in “Forward" gear, use timing light and check flywheel timing mark alignment with crankcase cover/cylinder block split line. Idle timing should be 5° B.T.D.C.
3, Rotate flywheel to bring piston to TDC position. Check that crankcase cover/cylinder block split line (a) is aligned with TDC mark (b) on flywheeL
a - Crankcase Cover/Cylinder Block Split Line b - TDC Timing Mark of Flywheel
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