Mercury 40 4-Stroke User Manual

MAINTENANCE
55
1. Remove the spark plug boots. Twist the rubber boots slightly and pull off.
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2. Remove the spark plugs to inspect. Replace spark plug if electrode is worn or the insulator is
rough, cracked, broken, blistered, or fouled.
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3. Set the spark plug gap to specification.
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Spark Plug
Spark plug gap 1.0 mm (0.040 in.)
4. Before installing spark plugs, clean off any dirt on the spark plug seats. Install plugs finger-tight,
and then tighten 1/4 turn or torque to specifications.
Description
Nm lb. in. lb. ft.
Spark plug 27 20
Fuse Replacement
IMPORTANT: Always carry spare 20 amp fuses.
The electrical wiring circuits on the outboard are protected from overload by fuses in the wiring. If a fuse
is blown, try to locate and correct the cause of the overload. If the cause is not found, the fuse may blow
again.

Mercury 40 4-Stroke Specifications

General

Engine Type	4-Stroke
Horsepower	40 hp
Cylinders	3
Fuel Induction System	Electronic Fuel Injection (EFI)
Starting	Electric
Displacement	747 cc
Shaft Length	20 in
Dry Weight	216 lbs
Steering	Remote
Alternator Amp	18 amp / 226 watt
Full Throttle RPM	5500 - 6000 RPM