Mercury 300R HD CMS Mechanical Operation And Maintenance Manual page 40

OVERSPEED REV LIMIT
The overspeed rev limit is set at an RPM greater than the operating range. In
the event that the engine is operated at an RPM greater than or equal to the
overspeed limit, the PCM does not allow the engine to maintain the power
requested by the operator. Refer to General Information ‑ Specification to
determine this engine's RPM limit.
Upon reaching the beginning of the overspeed rev limit, Engine Guardian will
cut fuel to one bank of cylinders. If the operator does not reduce engine speed,
Engine Guardian will cut the fuel to all cylinders until the engine speed has
dropped below the rev limit. There is no audible warning while Engine Guardian
overspeed limit is active.
SMARTCRAFT PRODUCT
A Mercury SmartCraft System instrument package can be purchased for this
outboard. A few of the functions the instrument package will display are engine
RPM, coolant temperature, oil pressure, water pressure, battery voltage, fuel
consumption, and engine operating hours.
The SmartCraft instrument package will also aid in Engine Guardian
diagnostics. The SmartCraft instrument package will display critical engine
alarm data and potential problems.
EXHAUST GAS OVER TEMPERATURE
When the Engine Guardian system detects the exhaust gas temperature is high
(fault code 2124‑20), the warning horn will beep and the engine RPM will be
limited. SmartCraft gauges which have the ability display text, will alert the
operator with a short text, long text, and the action which the operator should
follow. This Guardian warning and engine power reduction can possibly be
corrected by inspecting the gear housing water inlet for blockage and the
exhaust water strainer for blockage. Refer to Maintenance ‑ Exhaust Water
Strainer Inspection.
Short text
Long text
Stop engine and check for plugged exhaust water strainer. If
Action condition persists return to port immediately. Service engine
1. Stop the engine.
2. Check the gear housing water inlet for blockage.
3. Check the exhaust water strainer for blockage. Refer to Maintenance ‑
Exhaust Water Strainer Inspection.
4. If there is no blockage and the condition persists, return to port
immediately.
FEATURES AND CONTROLS
SmartCraft Displayed Text
Engine exhaust manifold is overheating
Critical ‑ Overtemp
before next use.
30
eng