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Mercury
Mercury 90HP
$10,100.00$11,500.00Save $1,400.00
The 2025 Mercury 90HP long shaft outboard is a powerful and fuel-efficient four-stroke EFI engine designed for fishing boats, pontoons, and mid-size vessels with a 20-inch transom. It delivers smooth, quiet performance with reliable acceleration.
Horsepower
90 HP
Fuel Type
gasoline
Year
2025
Displacement
2.1L
Stroke
4-stroke
Rated Output
67kW / 90mhp
Rated Speed
6000rpm
In Stock (3 available)
Free shipping on orders over $500
90-day warranty included
Description
The 2025 Mercury 90HP FourStroke is a reliable, fuel-efficient 4-stroke outboard engine built for a wide range of boats including pontoons, aluminum fishing boats, and mid-size hulls. It combines smooth performance, EFI fuel delivery, power trim & tilt, and SmartCraft compatibility for modern digital engine monitoring, making it a great choice for both recreational and workboat use.
Specifications
SKUM6011
BrandMercury
CategoryOutboard Engines
ConditionNew
Horsepower90 HP
Fuel Typegasoline
Year2025
Displacement2.1L
No. of Cylinders4 cylinders
Stroke4-stroke
Shaft Length20
Weight359.00 lbs
Rated Output67kW / 90mhp
Rated Speed6000rpm
Cylinder Bore x Stroke79 mm × 81 mm / 3.11 in × 3.19 in
Combustion System4-stroke, SOHC, electronic fuel injection (EFI)
AspirationNatural
Alternator35-amp
Dry Weight163 kh / 359lbs
ControlsMechanical
Frequently Asked Questions
What is the Mercury 90 HP outboard motor?
The Mercury 90 HP outboard is a 90-horsepower, four-stroke marine engine designed for recreational boating, fishing, water sports, and utility applications. It uses inline-4 EFI technology for smooth and efficient performance.
What type of engine does the Mercury 90 HP use?
It features a 4-cylinder, 8-valve inline 4, four-stroke engine with electronic fuel injection (EFI) for reliable starts, efficient fuel delivery, and lower emissions.
How much horsepower does it produce?
As the model name suggests, the engine produces 90 horsepower (about 67 kW).
What fuel should the Mercury 90 HP use?
Use unleaded gasoline with a minimum octane rating of 87 (R+M)/2 or 90 RON, and no more than about 10 % ethanol.
What is the recommended oil for this engine?
Mercury generally recommends Mercury FourStroke engine oil (e.g., 10W-30) for proper lubrication and performance.
What is the ideal RPM range at full throttle?
The recommended wide-open throttle (WOT) RPM range for the Mercury 90 HP is approximately 5000 – 6000 RPM.
What shaft lengths are available?
Common shaft length options include 20 in (508 mm) and 25 in (635 mm) to match different boat transoms and hull designs.
Is the Mercury 90 HP fuel-efficient?
Yes — thanks to its electronic fuel injection and efficient four-stroke design, the Mercury 90 HP offers good fuel economy and cleaner running compared with older two-stroke engines.
Can the Mercury 90 HP be used in saltwater?
Yes. The engine has corrosion-resistant coatings and components for saltwater use, but you should flush with fresh water after saltwater boating and perform regular corrosion protection for best long-term durability.
What boats is the Mercury 90 HP best suited for?
This engine is typically used on: Mid-size fishing boats Pontoon boats Small cruisers RIBs and utility boats Watersports craft.
Does the Mercury 90 HP support digital integration?
Yes. It is compatible with Mercury SmartCraft digital systems for integrated engine monitoring, diagnostics, and performance data display.
What maintenance does the Mercury 90 HP need?
Routine maintenance includes: Engine oil and filter changes Lower unit gear oil changes Spark plug checks and replacement Cooling system checks Fuel filter replacement.
