Spark Plug Inspection And Replacement - Mercury 40 SeaPro Operation, Maintenance & Installation Manual

10. Install the spark plug leads.

Spark Plug Inspection and Replacement

Damaged spark plug boots may emit sparks that can ignite fuel vapors under
the engine cowl, resulting in serious injury or death from a fire or explosion.
To avoid damaging the spark plug boots, do not use any sharp object or
metal tool to remove the spark plug boots.
1. Remove the spark plug boots. Twist the rubber boots slightly and pull off.
2. Remove the spark plugs to inspect. Replace spark plug if electrode is
worn or the insulator is rough, cracked, broken, blistered, or fouled.
3. Set the spark plug gap to specification.
Spark Plug
Spark plug gap
4. Before installing spark plugs, clean off any dirt on the spark plug seats.
Install plugs finger‑tight, and then tighten 1/4 turn or torque to
specifications.
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MAINTENANCE
WARNING
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26899
26946
26947
1.0 mm (0.040 in.)