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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
Buy used 2025 Mercury 90 HP FourStroke outboard engines or explore new engines for sale built for dependable marine performance and efficient everyday boating. The 2025 Mercury 90 HP FourStroke is a popular choice for buyers searching for reliable four-stroke outboard motors, replacement boat engines, and fuel-efficient marine propulsion systems. Designed for smooth operation, responsive power delivery, and long-term durability, this outboard supports recreational and commercial marine applications.
The 2025 Mercury 90 HP FourStroke is engineered to deliver balanced horsepower, excellent fuel economy, and dependable performance across changing water conditions. Its modern marine platform supports efficient cruising while maintaining smooth and quiet engine operation.
Equipped with Electronic Fuel Injection (EFI), the engine optimizes fuel delivery for cleaner combustion and improved throttle response. This advanced fuel system enhances starting reliability and helps maintain consistent performance throughout the operating range.
Power trim and tilt functionality provide easier boat handling and improved control while adapting efficiently to different marine environments. SmartCraft compatibility adds advanced digital engine monitoring, allowing improved visibility into engine performance and operational management.
Built for versatility and dependable ownership, the Mercury 90 HP FourStroke performs efficiently across multiple boating applications. Its durable design supports everyday marine use while maintaining efficient operation and long-term reliability.
Ideal for pontoon boats, aluminum fishing boats, mid-size hulls, recreational vessels, and workboat applications, the 2025 Mercury 90 HP FourStroke remains a trusted solution for dependable marine propulsion.
Key Features:
• 2025 Mercury 90 HP FourStroke outboard engine
• Fuel-efficient four-stroke marine platform
• Electronic Fuel Injection (EFI) system
• Smooth acceleration and quiet operation
• Power trim and tilt functionality
• SmartCraft digital monitoring compatibility
• Responsive throttle performance
• Reliable starting capability
• Suitable for recreational and workboat use
• Built for dependable long-term operation
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.
