Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 55Get this manual
7Low Oil Pressure Protection: Limits the engine RPM to 2000 if oil pressure drops below 2.25 +0.75 psiThe ECM will sound the low oil pressure warning horn (intermittent second on1 second off) and turn on the optional Low Oil Pressure Warning lampLowoll pressure warning will reset by shutting the engine off and restarting at normal oil pressure Flywheel Assembly
NOTE: The ECM controls all timing operationsThere are no timing adjustment required on this engine
Crank Position Sensor
The flywheel assembly contains six permanently charged magnet segments which are bonded and retained to the inner wall of the flywheelEach magnet contains north and south pole providing 12 pole system
Ignition Coil
Contains permanent magnet and is positioned 0.030 0.010" (0.762 0.254mm) from the flywheel teethThe timed passing of the flywheel teeth through the sensor's magnetic field enables the ECM to determine engine RPM and crankshaft angle