Ignition Components; Flywheel - Mercury 15 EFI FourStroke Service Manual

Ignition Components

Flywheel

The flywheel is weighted and balanced to improve engine running characteristics. The flywheel is secured to the crankshaft
with a washer and nut. The flywheel has a ring gear that is used with the optional starter motor to start the engine electrically.
The top of the flywheel is cast with notches to engage the recoil starter, for manual starting.
Below the ring gear, the flywheel is cast with a timing key. As the timing key passes the crankshaft position sensor (CPS), the
CPS generates an electrical pulse that is sent to the engine control module (ECM). The ECM calculates the speed and position
of the crankshaft according to the frequency and timing of the pulses. The ECM then uses the speed and position information to
regulate ignition and fuel injector timing.
The flywheel also has magnets on the inside circumference to generate voltage within the stator. Refer to Stator, for additional
information.
Flywheel Removal
1. Remove the air box and recoil starter.
• It is easiest to remove and install these two items together.
• Refer to Section 3C ‑ Air Box Removal and Section 8A ‑ Recoil Starter.
2. Disconnect the spark plug leads from the spark plugs.
3. Hold the flywheel with a flywheel holding tool, and remove the flywheel nut and washer.
Flywheel Holding Tool
4. Fasten a three‑point flywheel puller onto the flywheel. Do not use a jaw type puller.
NOTE: Do not use heat or strike the flywheel.
5. Loosen the flywheel using the puller.
6. Remove the flywheel and retain the flywheel key.
90-8M0125265 eng NOVEMBER 2017
a
a - Flywheel holding tool
b - Breaker bar and socket
b
62876
91‑ 52344
63875
© 2018 Mercury Marine
Ignition
Page 2A-13