Replaceable Jet Drive Shear Key - Mercury 25 Jet 4-Stroke Manual

LOW OIL PRESSURE
The warning system is activated if the oil pressure drops too low.
First, stop the engine and check the oil level. Add oil if necessary.
If the oil is at the recommended level and the warning horn
continues to sound, consult your dealer. Engine speed will be
limited to 2800 RPM, however you should not continue to operate
the engine.
ENGINE OVER-SPEED LIMITER
The outboard is equipped with an engine over‑speed limiter which
limits the engine maximum RPM. This protects the engine from
mechanical damage.
Some causes of engine over‑speed are as follows:
• Outboard mounted too high on the transom
• Worn jet pump impeller or liner
• Incorrect jet pump impeller clearance adjustment
• Tilting the outboard out beyond a vertical position
• Cavitation of the impeller due to rough water or obstruction in
the boat hull
• Blockage of the water intake
When the engine over‑speed limiter is activated, it will reduce
ignition voltage to momentarily decrease the engine speed.
Excessive over‑speed (above 6300 RPM) results in cutout of the
cylinders to prevent operation above this limit.

Replaceable Jet Drive Shear Key

The jet drive is equipped with a shear key to protect it in the event
of a lodged impeller. The shear key can be reached by removing
the water intake housing and impeller. Refer to Maintenance -
Impeller Removal and Installation.
FEATURES & CONTROLS
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