2025 Mercury FourStroke 9.9 HP Outboard Motor – Compact Power, Modern Efficiency

Step up your boating game with the 2025 Mercury FourStroke 9.9 hp outboard—a lightweight, fuel-efficient, and reliable 4-stroke engine built for small watercraft, tenders, inflatables, and backup power use. With its modern engineering, electronic fuel injection (EFI), and refined construction, the 9.9 hp FourStroke delivers responsive performance, smooth operation, and years of dependable service.

As part of Mercury’s trusted FourStroke line, this engine combines proven marine design with features once reserved for larger motors, offering a compelling balance of power, portability, and efficiency.

Key Features & Technical Highlights

• Horsepower: 9.9 hp (7.4 kW) motor class

• Engine Type: Inline-2, 4-stroke with EFI (Electronic Fuel Injection)

• Displacement: ~209 cc (12.8 CID) for compact performance

• Ignition & Start: Digital CDI + manual start (EFI ensures reliable ignition)

• Alternator Output: 12-amp (approx. 145 W) charging capability for electronics

• Full Throttle RPM: 5,000 – 6,000 rpm range

• Steering: Tiller handle (standard model) for direct control

• Shaft Length: 15″ (short shaft) commonly offered version

• Weight & Build: Lightweight construction for ease of handling and mounting

• Quiet, Smooth Operation: Designed to minimize vibration and noise, improving comfort

• Corrosion Resistance: Marine-grade coatings and materials to withstand saltwater use

Advantages & Benefits

1. Portable & Light – Ideal for boats where weight and ease of mounting matter.

2. Fuel-Efficient Design – EFI manages fuel delivery precisely to reduce consumption.

3. Reliable Starting & Operation – EFI improves cold start performance and consistent running.

4. Electronics Ready – Alternator supports power for lights, pumps, GPS, or radios.

5. Easy Maintenance – Simplified 4-stroke design avoids the fuss of 2-stroke fuel/oil mixing.

6. Versatile Use Cases – Suitable as main power for small crafts or auxiliary power on larger boats.

7. Quiet & Refined – Lower noise and vibration enhance the riding experience.

8. Brand Trust & Support – Mercury’s global support network ensures parts and service availability.

Ideal Applications

• Dinghies and tenders

• Inflatable boats and RIBs

• Fishing skiffs and shallow-water crafts

• Auxiliary engines on larger vessels

• Small recreational boats needing a quiet, lightweight motor