Mercury 20 HP Rope & Electric Start Long Shaft Outboard Motor

The Mercury FourStroke 20 ELH EFI is a 4-stroke outboard marine engine designed for small fiberglass, aluminum, or inflatable boats requiring a long shaft, suitable for boats 2.5–5 meters in length. It features a 20 HP / 14.9 kW, 333 cc 2-cylinder engine. The FourStroke 20 ELH EFI with its 333 cc EFI FourStroke engine offers economical and reliable power to small and medium-sized boat users.

FourStroke 20 ELH EFI Series Features and Technology Advantages

The 2-cylinder design offers balanced power with a compact and lightweight design. EFI injection ensures reliable starting without requiring a manual fuel system.

• 2-Cylinder Engine (333 cc): The 2-cylinder design offers balanced power with a compact and lightweight design
• Long Shaft (508 mm (20")): The propeller operates at optimum depth at the correct transom height
• EFI Electronic Injection: No primer bulb required — automatic fuel system priming before turning the key
• Electric Start with Manual Backup: Easy starting with low battery consumption; pull-start system as backup
• Manual Trim: Manual adjustment of the transom angle — simple and reliable mechanical structure
• 12-Liter Internal Tank: Ready for daily short-distance use; external tank input available

Long Shaft — What Boat Type Is It Suitable For?

The long shaft (508 mm (20")) is suitable for the majority of inflatable boat, aluminum, and fiberglass boat models. For boats with a transom height of 381 mm, a short shaft model should be preferred.

Technical Specifications

Who Is This Engine For?

• 2.5–5 meter small to medium-sized boats: economical EFI power
• Fishing and coastal use: quiet 4-stroke operation
• Inflatable boats and RIBs: lightweight engine and balanced thrust
• Auxiliary engine: access to reliable Mercury service network

Maintenance and Longevity

4-stroke Mercury engines operate trouble-free for many years with regular oil changes and end-of-season maintenance protocols. The impeller of the water-cooled system should be checked every 100 hours or every two seasons. Fresh water flushing is mandatory after every use in saltwater.

Related maintenance categories: Maintenance Kit | Engine Oil | Impeller | Mercury Spare Parts

Frequently Asked Questions

What boat size is the Mercury FourStroke 20 HP engine suitable for?

20 HP power can be suitable for different sizes depending on boat weight and type. General rule: 15–20 kg of boat weight per HP. Always check the maximum engine power recommended by the boat manufacturer.

What advantage does the EFI system offer over a carbureted engine?

EFI (Electronic Fuel Injection) does not require a primer bulb or choke adjustment. It provides reliable starting in cold weather and at high altitudes, consistent power output, and lower fuel consumption compared to carbureted alternatives.

What are the maintenance intervals for the Mercury FourStroke?

Oil change at the first 20 hours, then every 100 hours or once per season. Impeller check every two seasons. Fresh water flushing is mandatory after every use in saltwater. Fuel system protection is recommended at the end of the season.

Which boat and inflatable boat brands is the FourStroke 20 ELH EFI compatible with?

Mercury outboard engines are compatible with many fiberglass, aluminum, and inflatable boat models thanks to their universal transom clamp or transom mounting system. The only criteria are your boat's 508 mm (20") transom height and the maximum engine power approved by the manufacturer. You can get compatibility confirmation from Clever Marin by sharing your boat model.

Related Products and Categories

• Mercury Outboard Motors
• Mercury Marine Products
• Mercury Spare Parts
• Mercury 2.5–30 HP FourStroke
• Mercury 40–60 HP FourStroke
• Outboard Motors
• Boat Engines
• Maintenance Kit
• Impeller
• Anode

Is This the Right Configuration for Your Boat?

Share your boat model, transom height, and intended use — let's confirm together the suitability of the Mercury FourStroke 20 ELH EFI engine for your boat and the correct shaft selection.