Mercury 9.9 ELPT Specifications
| Engine Model: Mercury 9.9 ELPT |
| Engine Type: 4-stroke 2-cylinder SOHC gasoline outboard engine |
| Total Displacement: 12.8 cu.in (209 cc) |
| Rated Engine Power: 9.9 Hp (7.3 kW) at 6000 rpm |
| Fuel System: Carburetor or electronic fuel fnjection (EFI) |
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The Mercury 9.9 ELPT represents a versatile and
portable outboard solution, prized for its smooth operation, fuel
efficiency, and ease of use. Its ELPT designation indicates an Electric
start, Long shaft, Power Tilt model, offering push-button convenience
and effortless trim adjustment. A key differentiator for many models is
the Command Thrust (CT) gearcase option, which features a larger
gearcase and a specially designed four-blade propeller to deliver
superior thrust and positive control, particularly for heavier boats
like pontoons or smaller sailboats.
The powerhead is a robust inline two-cylinder four-stroke, featuring
Electronic Fuel Injection (EFI) on later models for instant starting and
optimized performance in all weather conditions. The engine incorporates
an operator warning system for low oil pressure and over-rev conditions,
and a convenient no-spill oil change system simplifies maintenance. Its
lightweight construction and integrated carry handle make it easy to
transport and maneuver.
Maximum Power Output: 9.9 Hp (7.3 kW) at the propeller shaft.
Full Throttle Operating Range: 5000 to 6000 RPM.
Engine Type: Inline 2-cylinder, four-stroke with Single Overhead
Camshaft (SOHC).
Displacement: 209 cc (12.8 cubic inches).
Bore and Stroke: 55 mm (2.16 inches) bore and 44 mm (1.73 inches)
stroke.
Fuel System: Modern models feature Electronic Fuel Injection (EFI) for
reliable starting and improved fuel efficiency, with some sources citing
up to 27% better economy than carbureted predecessors. Some listings and
older models may be carbureted.
Ignition System: Capacitor Discharge Ignition (CDI) with electronic
spark advance.
Alternator Output: Most models are equipped with a 6 amp (76 watt)
alternator.
Some newer or differently configured models may feature a 12 amp (145
watt) alternator.
Starting System: Electric start with a manual recoil backup.
Steering: Remote control (denoted by the "R" in ELPT).
Engine Management: Features an operator warning system for low oil
pressure and engine over-rev, which can limit engine speed to protect
the powerhead.
Compatible Fuel: Unleaded regular gasoline with a minimum octane rating
of 87, containing up to 10 percent ethanol. Recommended Oil: Mercury
FourStroke Oil 10W-30 is commonly specified.
The foundation of the Mercury 9.9 ELPT is a compact and robust inline
two-cylinder block designed for smooth operation and long-term
durability. Configuration: Inline 2-cylinder. Displacement: 208-209 cc
(12.8 cubic inches). Bore and Stroke: The cylinder bore is 55 mm (2.16
inches) and the piston stroke is 44 mm (1.73 inches).
Engine Type: Four-stroke, providing clean operation, exceptional fuel
efficiency, and quiet running without the need for pre-mixing fuel and
oil. It is among the lightest engines in its class, enhancing
portability.
The cylinder head assembly is designed for efficient gas exchange and
maintenance-free operation, contributing to the engine's reliability.
Valvetrain Design: Single Overhead Camshaft (SOHC) configuration with
two valves per cylinder.
Valves per Cylinder: Two, resulting in a total of four valves for the
engine. Valve Train Maintenance: The valve train features a
maintenance-free design, eliminating the need for periodic valve
adjustments for the life of the engine. Fuel Induction: The valvetrain
supports either the Electronic Fuel Injection (EFI) or carbureted fuel
system, depending on the model year.
The fuel system on modern Mercury 9.9 ELPT models utilizes advanced
electronic controls to provide enhanced reliability and precise fuel
delivery. Induction System: Electronic Fuel Injection (EFI) provides
precise fuel metering for effortless starting, controlled throttle
response, and superior fuel efficiency across the entire RPM range.
Fuel Delivery: An electric fuel pump delivers fuel from the remote tank
to the injector at the required pressure. The engine comes standard with
a 12-liter (3.2-gallon) remote fuel tank. Recommended Fuel: Minimum
87-octane unleaded petrol is specified to ensure proper combustion.
The four-stroke design incorporates a self-contained, high-pressure
wet-sump lubrication system ensuring all moving parts are properly
oiled. System Type: Wet sump, with engine oil stored in a sump within
the oil pan. Oil Capacity: The engine oil capacity is 0.8 liters (27.0
fluid ounces).
Oil Filling and Change: The engine features a convenient no-spill
oil-change system for cleaner and easier maintenance. Some models do not
have a traditional oil filter to change, simplifying routine service. A
top-cowl service door allows for easy oil checks and fills.
Recommended Oil: Mercury FourStroke Oil 10W-30 is the specified
lubricant for optimal protection and performance. Low Oil Pressure
Warning: A warning system alerts the operator if engine oil pressure is
low, which can limit engine speed to prevent damage.
To manage engine temperature, the Mercury 9.9 ELPT uses a positive
displacement water pump for raw water cooling. System Type: Water-cooled
with a thermostat, drawing outside water through an intake in the
gearcase to cool the engine.
Core Components: A rubber-impeller water pump, driven by the driveshaft,
pulls water from the lake or ocean. A thermostat regulates the flow to
maintain the engine at its optimal operating temperature. Flushing
System: A quick-connect flush attachment is provided for easy flushing
of the cooling system with a garden hose after operation in salt or
polluted water.
| Mid Section and Lower Unit |
The mid-section houses the exhaust and driveshaft, while the lower unit
is engineered for durability. The Command Thrust (CT) gearcase is a
defining feature for many 9.9 ELPT models.
Gearcase Design: Many 9.9 ELPT models feature the Command Thrust (CT)
gearcase. This design incorporates larger, more robust components and a
longer housing to place the propeller deeper, below turbulent water, for
improved thrust and control on heavier boats. The anti-ventilation plate
is also enlarged to prevent air from being drawn into the propeller.
Gear Ratio: The gear ratio for Command Thrust models is 2.42:1. Some
listings for 9.9 ELPT models also show a ratio of 2.08:1, which may
indicate a standard gearcase or a different model year.
Gear Shift: Standard forward-neutral-reverse (F-N-R) shifting operation.
Exhaust: Through-propeller exhaust release for quieter operation.
Gearcase Lubrication: The gearcase holds dedicated high-grade marine
gear lubricant. The capacity is approximately 0.370 liters.
The engine is equipped with a power tilt system for effortless
adjustment of the engine's angle relative to the transom. System Type:
Power Tilt (denoted by the "PT" in ELPT), controlled by a
dashboard-mounted switch. This system is designed for tilting the engine
out of the water and may not offer on-the-fly trim adjustment in all
models.
Tilt Function: The power tilt lifts the engine out of the water for
trailering, launching, beaching, or shallow water anchoring. Trim
Positions: Manual ratcheting trim positions are often provided to preset
the engine angle for optimal performance. Shallow Water Drive: The
engine features a shallow water trim range of 16 deg, allowing operation
in very shallow water.
CT Propeller Design: Models equipped with the Command Thrust gearcase
utilize a larger-diameter, four-blade, low-pitch propeller designed for
superior thrust and positive control, especially at low trolling speeds.
The propeller is 20% larger than those used on standard gearcases.
Standard Propeller Range: For non-CT models or as a general range,
propellers with a pitch of 5 to 11.5 inches are applicable for this
engine family. Included Propeller: The engine is typically delivered
with a propeller installed, often a 4-blade, 7-inch pitch model for CT
versions.
Shaft Length: Long shaft (L) model with a shaft length of 508 mm (20
inches), designed for boats with a standard transom height.
Dry Weight: The weight varies slightly by model, year, and specific
configuration. The lightest models are available at approximately 38 kg
(84 lbs). More commonly, Command Thrust models weigh around 44 to 49 kg
(97 to 108 lbs).
Routine Maintenance (Every 100 Hours /
Annually):
Change the engine oil using the no-spill system.
Replace the gearcase lubricant.
Inspect and clean or replace the spark plugs.
Check and clean the fuel filter.
Inspect the fuel system for leaks or deterioration.
Check and clean the anti-corrosion anodes, replacing them if more than
50 percent eroded.
Lubricate all moving parts and pivot points.
Check the tightness of bolts, nuts, and other fasteners.
Inspect the battery condition and electrolyte levels on electric start
models.
Critical Maintenance Items:
Water Pump Impeller: Should be replaced periodically as preventative
maintenance to prevent overheating due to impeller failure.
Valve Clearance: The SOHC valvetrain is designed to be maintenance-free,
requiring no periodic valve adjustments.
Corrosion Protection: Regularly inspect sacrificial anodes and replace
when deteriorated.
Flushing: Flush the cooling system with fresh water after each use in
saltwater or polluted water using the quick-connect flush system.
Spark Plugs: Torque to specifications listed in the operator's manual or
service manual.
Propeller Nut: 40 Nm (30 lb-ft).
Gearcase Mounting Nuts: 40 Nm (30 lb-ft).
Engine Mounting Bolts (to transom): 55-60 Nm (41-44 lb-ft).
Auxiliary Power for Sailboats: Its reliability and high-thrust CT option
make it a popular choice as a dependable auxiliary engine for daysailers
and cruising sailboats up to approximately 9 meters (30 feet). Small
Fishing Boats: The engine is perfectly suited for aluminum tiller boats,
jon boats, utility boats, and inflatable soft-hull boats used for
fishing in inland and coastal waters.
Pontoon Boats: The Command Thrust version provides the necessary thrust
to efficiently maneuver smaller pontoon boats, offering positive control
in tight spaces. Dinghies and Tenders: Its light weight and portability
make it an excellent choice for powering rigid or inflatable tenders for
larger yachts.
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