Engine Overspeed (Excessive Rpm); Performance Loss; Battery Will Not Hold Charge - Mercury 25 Jet FourStroke Operation, Maintenance And Installation Manual

• Incorrect setup and adjustments.
• Fuel is being restricted to the engine.
a. Engine fuel filter is obstructed. Refer to Maintenance section.
b. Fuel tank filter obstructed.
c. Stuck antisiphon valve located on permanently built‑in type fuel tanks.
d. Fuel line is kinked or pinched.
• Fuel pump failure.
• Ignition system component failure.

Engine Overspeed (Excessive RPM)

POSSIBLE CAUSES
• 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.

Performance Loss

POSSIBLE CAUSES
• Throttle not fully open.
• Damaged impeller.
• Incorrect engine timing, adjustments, or setup.
• Boat overloaded or load improperly distributed.
• Excessive water in bilge.
• Boat bottom is dirty or damaged.

Battery Will Not Hold Charge

POSSIBLE CAUSES
• Battery connections are loose or corroded.
• Low electrolyte level in battery.
• Worn out or inefficient battery.
• Excessive use of electrical accessories.
• Defective rectifier, alternator, or voltage regulator.
eng
TROUBLESHOOTING
75