1988-1992 Mercury Force 5HP Outboards Service Manual, Page 117Get this manual
z BIM IGNITION SYSTEM (1990 and Newer)
1Theory of Operation This system operates the same way as the older breaker point magneto systems except there are no breaker points or condensersThe triggering mechanism is encapsulated in the coil assembly to form compact, self contained ignition systemThe primary windings of the ignition coil are charged by the flywheel magnets the same way as the coil is charged in breaker point systemThe flywheel magnets also activate smaller trigger coil, which is encapsulated within the body of the coil assemblyThis trigger coil, in turn, activates an electronic switch (SeR), which opens like set of breaker points and allows the magnetic field in the primary windings to collapse, generating high voltage in the secondaryThe high voltage in the secondary of the coil is released through the spark plug lead and jumps the gap in the spark plug