The Mercury 40HP 4-Stroke EFI Outboard delivers instant throttle response and consistent power across the entire RPM range. Featuring a high-displacement 747 cc inline 3-cylinder design, it easily powers mid-sized aluminum hulls, pontoons, and fiberglass skiffs. Designed for low vibration and ultra-quiet running, this motor lets you enjoy every moment on the water. If you are exploring different power options or brands, browse our complete selection of 4-Stroke Outboards to find the right engine for your boat.
Key Performance & Smart Features
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Electronic Fuel Injection (EFI): Battery-free EFI technology ensures effortless turn-key starting in cold or hot weather, along with optimal fuel efficiency and clean emissions.
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SmartCraft® Digital Engine Monitoring: Connects directly with Mercury SmartCraft gauges and multi-function displays to provide real-time engine diagnostics, fuel management, and trolling control.
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High-Output Alternator: Keeps onboard electronics, fishfinders, and nav lights fully charged with a high-capacity charging system.
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Low-Vibration Mounting: Vibration-dampening engine mounts minimize noise and hull shake for a smoother, quieter ride. Have questions about gauge or rigging setups? Visit our FAQs page.
Corrosion Protection & Built-to-Last Durability
Designed to withstand both saltwater and freshwater environments, Mercury utilizes a multi-step anti-corrosion coating process featuring MercFusion painting technology, low-copper aluminum alloys, and strategically placed sacrificial anodes. A freshwater flushing system makes routine maintenance fast and effortless. For full details on operating coverage, consult our official Warranty Policy.
Technical Specifications
| Specification | Details |
| Horsepower | 40 HP @ 5800 RPM |
| Engine Type | Inline 3-Cylinder SOHC 4-Stroke |
| Displacement | 747 cc (45.6 cu in) |
| Bore x Stroke | 65 mm x 75 mm |
| Full Throttle RPM Range | 5500 – 6000 RPM |
| Fuel Delivery | Electronic Fuel Injection (EFI) |
| Starting System | Electric Start |
| Cooling System | Water-Cooled with Thermostatic Control |
| Alternator Output | 18 Amp (226 Watt) |
| Gear Ratio | 2.00:1 |
| Dry Weight | 118 kg (260 lbs) |
| Transom Height | 20″ (Long Shaft) |
What’s Included in the Package
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1x Mercury 40HP 4-Stroke EFI Outboard Engine
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1x Aluminum Propeller (pitched to customer specifications)
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1x Side-Mount Remote Control Box & Harness
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1x Digital Gauge Kit
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1x Safety Lanyard & Kill Switch
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1x Owner’s Manual & Rigging Documentation
For crate packaging specifications and shipping logistics, please view our Shipping & Freight Policy.
Scientific & Technical References
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To review environmental compliance guidelines for marine outboards, visit the California Air Resources Board (CARB) Marine Engine Regulations.
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For detailed technical standards on electronic fuel injection and marine diagnostic management, consult the Society of Automotive Engineers (SAE) Marine Standards.
Frequently Asked Questions (FAQs)
1. Is the Mercury 40HP 4-Stroke EFI suitable for pontoon and aluminum fishing boats?
Yes. Thanks to its strong low-end torque and lightweight 3-cylinder design, it is one of the most popular repower choices for aluminum bass boats, pontoons, side consoles, and large inflatable boats.
2. Does this motor start easily in cold weather?
Yes. Thanks to Electronic Fuel Injection (EFI), the motor features turn-key starting without requiring a choke, ensuring quick, reliable starts in all weather conditions.
3. What fuel octane is recommended for the Mercury 40HP EFI?
It is optimized to run on standard 87 pump octane unleaded gasoline. Using ethanol-free marine fuel (or adding a quality marine fuel stabilizer) is recommended to protect the EFI fuel system.
4. What happens if my freight shipment arrives damaged?
All motor shipments are fully insured. In the unlikely event of physical damage upon delivery, please consult our Refund & Returns Policy or reach out immediately via our Contact Us page.
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