MERCURY 20 HP EFI 20MH OUTBOARD MOTOR

Description

The Mercury 20 HP EFI 20MH outboard motor is about as much power as you can get in a motor that’s still called portable. It uses Mercury’s 333 cc fuel injected twin, weighs about 103 pounds, starts with a pull of the cord and no battery, and has a 15 inch short shaft and the one handed multi-function tiller. A 3.2 gallon fuel tank comes in the box. We have it for sale new with the Mercury factory warranty and ship worldwide.

It’s the same weight as the 15 hp EFI, but tuned for 20 horsepower. If your boat is rated for 20 and you want quick planing and brisk acceleration from a simple, battery free motor, the Mercury 20 HP EFI 20MH outboard motor is a very good buy.

On this page:

• Why the Mercury 20 HP EFI 20MH outboard motor
• 20 hp vs 15 hp
• Boats it suits
• Features
• Specifications
• Maintenance
• Alternatives
• Price and shipping
• FAQ

Why the Mercury 20 HP EFI 20MH outboard motor

Power to weight. At around 103 pounds, this is one of the lightest 20 hp four strokes around. The large 333 cc twin gives strong low end torque that gets a boat onto the plane quickly, and a tuned intake manifold gives sharp throttle response. On a 14 foot aluminum boat with two people, you feel the difference from a 9.9 or 15 straight away: quicker out of the hole, more top speed, and less strain at cruise.

Fuel injection keeps it simple. No choke, clean starts in any weather and a smooth idle. The EFI system runs from the pull of the cord on manual start models, so there’s no battery to buy or maintain. It’s also more economical than an old carbureted 20, so you get more running time from each tank.

Mercury fitted a heavy duty transom bracket, vibration absorbing wishbone mounts, an easy canister oil filter, shallow water drive and a quiet through the prop exhaust. Start in gear protection, a low oil pressure warning and ESG over rev protection are all standard.

Model code: 20 hp, M manual start, H tiller, no L means 15 inch short shaft, EFI electronic fuel injection.

20 hp vs 15 hp

The 15 and 20 hp EFI motors share the same powerhead and the same weight. The 20 is tuned to run a little higher in the rev range, with a full throttle band of 5,400 to 6,100 rpm, and gives noticeably more top speed and punch. If your boat is rated for 20 hp and no horsepower limit applies where you boat, most buyers choose the 20. The price step is small, and you get more performance for the same weight. If a 15 hp limit applies, or your boat’s plate says 15, the 15MH EFI is the one.

Boats the Mercury 20 HP EFI 20MH outboard motor suits

Measure from the top of the transom to the bottom of the hull. About 15 inches means this short shaft. About 20 inches means the 20MLH. Check your capacity plate for the maximum horsepower.

• Aluminum fishing boats of 14 to 15 feet with a low transom
• Larger jon boats and skiffs
• RIBs and inflatables around 4 to 4.5 metres, where rated
• Utility and work boats

On the water

Clip on the lanyard, put it in neutral and pull. No choke needed. It idles smoothly, shifts cleanly through the tiller, and jumps onto the plane with a load aboard. The shallow water drive helps in skinny water, and the exhaust exits through the prop hub for quiet running.

Buyer questions

“Is 103 pounds really portable?”

It’s a two person carry. Many owners trailer the boat with the motor on, but you can lift it off for storage or security.

“Can I add electric start?”

It’s simplest to buy the electric start 20EH from the start, which also has a 12 amp charging system.

Mercury 20 HP EFI 20MH outboard motor features

• Large 333 cc twin cylinder powerhead
• Electronic fuel injection, battery free starting
• Tuned intake for quick acceleration
• Heavy duty transom bracket
• Vibration absorbing wishbone mount
• Easy maintenance canister oil filter
• Multi-function tiller with forward, neutral and reverse
• Stainless steel water pump housing
• Zinc coated water passages, saltwater rated
• Sacrificial zinc anodes and trim tab
• Thermostat controlled cooling
• Shallow water drive
• Quiet through prop hub exhaust
• 3.2 gallon fuel tank and line
• Start in gear protection, low oil pressure warning, ESG over rev protection

Mercury 20 HP EFI 20MH outboard motor specifications

For the manufacturer’s own overview of the range, see Mercury’s FourStroke outboards page. Mercury updates details between model years, so if one spec really matters to your purchase, ask us and we’ll confirm it on the exact unit we ship.

Maintaining the Mercury 20 HP EFI 20MH outboard motor

Fuel: fresh 87 octane, up to 10% ethanol.

Oil: about 1 quart of 10W-30. Change oil and canister filter at 20 hours, then every 100 hours or yearly.

Gear case: change the lube yearly.

Cooling: check the telltale every start; flush after saltwater use.

If you’re newer to boating, the US Coast Guard boating safety site is worth a read. It’s written for US boaters, but the advice on kill cords, life jackets, fuel handling and navigation rules applies wherever you are in the world.

What electronic fuel injection means for you

The Mercury 20 HP EFI 20MH outboard motor uses electronic fuel injection, or EFI, instead of a carburetor. In plain terms, a small computer measures things like air temperature and engine load and injects exactly the right amount of fuel every time. You don’t need to fiddle with a choke. It starts easily whether it’s a frosty morning or a hot afternoon, it idles smoothly, and it responds cleanly when you open the throttle.

EFI is also less fussy about sitting. Carburetors have tiny jets and a fuel bowl that gum up when old fuel evaporates inside them. A sealed injection system is much more tolerant, although fresh fuel is still the best policy. And because the fuel is metered precisely, EFI motors tend to be more economical, which means more time on the water per tank.

Mercury’s small EFI engines can even start and run without a battery on manual start models: the pull of the cord generates enough power for the fuel injection system to fire. That’s a clever bit of engineering, and it means you get the benefits of EFI without having to carry a battery if you don’t want to.

Using your motor through the seasons

In spring, check the oil, fit fresh fuel, look over the fuel line and connectors for cracks, and run the engine on a flushing attachment or in a test tank before the first real trip. Look for a strong cooling stream and a smooth idle.

Through summer, the main jobs are fresh fuel, regular oil checks and rinsing after saltwater use. Keep an eye on the propeller for dings. A damaged prop costs you speed and fuel, and can cause vibration.

In autumn, before the boat is laid up, do the full storage routine: flush, change the oil and gear lube, deal with the fuel system as the owner’s manual describes, grease the moving parts and store the Mercury 20 HP EFI 20MH outboard motor somewhere dry. Twenty minutes in autumn saves hours of frustration in spring.

Paperwork, warranty and keeping records

When your Mercury 20 HP EFI 20MH outboard motor arrives, write down the serial number and keep it with your invoice. Take a photo of the serial plate on your phone too. If you ever need warranty work, a dealer will ask for both, and it makes the process much quicker. The Mercury factory warranty starts from the date of purchase, so hang on to that paperwork.

It is also worth keeping a simple log: date, engine hours if you have them, oil changes, gear lube changes, impeller replacements and anything unusual you noticed. It takes seconds after each service, and it adds real value if you ever sell the boat. Buyers pay more for an engine with a clear service history, and it helps any mechanic you work with understand the motor quickly.

Check your boat insurance as well. Many policies have specific requirements for outboard security, such as a lock on the clamps or bracket, and some ask for the serial number. Better to sort that out on day one than find out after a problem.

Why buy from us

We deal in outboard motors every day, and we would rather give you a straight answer than make a quick sale. If you are not sure the Mercury 20 HP EFI 20MH outboard motor is the right motor for your boat, message us with the make, model and length of the boat, how you use it and where you boat. We will tell you honestly whether it is a good match or whether something else would suit you better.

Every motor is packed carefully for the journey, and we keep you updated from dispatch to delivery with tracking. We ship worldwide, and we are happy to explain in advance what to expect with import duties and local taxes in your country, so there are no surprises when it arrives.

After you buy, we are still here. If you have questions about setup, break in or maintenance, just ask.

A small spares kit worth carrying

You do not need a workshop on board, but a few cheap parts turn most breakdowns into a ten minute fix. For the Mercury 20 HP EFI 20MH outboard motor, we suggest a spare spark plug and the right spanner, spare propeller hardware, a spare kill cord, a small bottle of engine oil, a couple of fuses if the motor has electrics, and a fuel line O ring or connector seal. Add some cable ties, a roll of self amalgamating tape and a basic multi tool.

Pack it all in a small dry bag, keep it in the boat, and check it every spring. Most owners never need it. The ones who do are very glad it was there.

A quick checklist before every trip

It sounds obvious, but most days that go wrong on the water start with something small that got missed at the dock. Before you head out with your Mercury 20 HP EFI 20MH outboard motor, run through this in your head:

• Enough fresh fuel for the trip, plus a sensible margin
• Engine oil checked and at the right level
• Motor mounted securely and everything tight
• Kill cord clipped to you, not left on the tiller or dash
• Cooling telltale spraying water once the engine is running
• Life jackets, a way to call for help, and a small spares kit aboard

It takes a minute or two. It is also the habit that separates relaxed boat owners from the ones waiting for a tow.

More questions we get asked

Can I install the Mercury 20 HP EFI 20MH outboard motor myself?

Many owners do, following the owner’s manual. If you are not confident with mounting, rigging or electrics, a local marine mechanic can set it up quickly, and it is money well spent.

How often does it need servicing?

Check the oil before every trip. Change the engine oil and gear lube at least once a year, or at the hour intervals in the owner’s manual, whichever comes first. Inspect the water pump impeller regularly and replace it as recommended.

What fuel should I use?

Fresh unleaded petrol of the octane rating shown in the specifications, with no more than 10% ethanol, unless it is a propane model. Old fuel is the cause of most running problems.

Can I pay in instalments?

Payment options vary by country. Contact us and we will tell you what is available for your order.

Why fuel care matters so much

If there’s one thing that decides whether an outboard starts first time or leaves you pulling and swearing at the ramp, it’s fuel. Modern petrol, especially with ethanol blended in, starts to break down within weeks. It absorbs moisture, separates and leaves gummy deposits that block the tiny passages in fuel systems.

For your Mercury 20 HP EFI 20MH outboard motor, the rules are simple. Buy fresh fuel from a busy station. Don’t store it for months in a can. Keep the tank vent closed when the boat isn’t in use. Use a fuel stabiliser if the boat will sit for more than a few weeks. And before any long lay up, deal with the fuel system as the owner’s manual describes, rather than leaving old fuel inside the engine. It’s a few minutes of effort that saves a lot of cost and frustration.

Your first run

The first hours of a new engine matter. For your Mercury 20 HP EFI 20MH outboard motor, follow the break in guidance in the owner’s manual. In broad terms: run at varied speeds, avoid long periods at full throttle, and don’t let it idle for ages either. Keep an eye on the cooling telltale and gauges, and listen for anything unusual.

After the break in period, change the engine oil and filter if fitted, and check the gear lube. From then on, just use it and service it on schedule. A well run in engine rewards you with smoother running and a longer life.

Real world setups for the Mercury 20 HP EFI 20MH outboard motor

The 14 foot tinny

A 14 foot aluminum boat with two anglers and gear. The Mercury 20 HP EFI 20MH outboard motor gets it planing quickly, cruises comfortably and still trolls smoothly at low revs. No battery means nothing to worry about over winter.

The fast RIB tender

A 4 metre RIB rated for 20 hp. It turns the tender into a quick little runabout, while staying light enough to lift off when the boat is hauled.

Setting up

With help, centre the motor on the transom, tighten the clamp screws firmly and tie a safety line to the boat. Set trim so it runs close to vertical with a normal load. Connect and prime the fuel, check the oil, clip on the lanyard, put it in neutral and pull. Check the telltale and follow the break in guidance.

Trailering with your motor

Most owners of a motor like the Mercury 20 HP EFI 20MH outboard motor leave it on the boat and trailer them together. A few habits protect the motor on the road. Use a transom saver or motor support bracket where recommended, so the motor isn’t bouncing on its tilt mechanism over bumps. Make sure there’s good ground clearance under the skeg. Close the fuel vent and disconnect the fuel line. And check the motor mounting bolts or clamps before every trip, because vibration on the road can loosen them over time.

At the ramp, lower the motor only once there’s enough water under it, and raise it before you drive the boat onto the trailer. It sounds obvious, but a surprising number of skegs and props get damaged at the ramp rather than out on the water.

Alternatives to the Mercury 20 HP EFI 20MH outboard motor

20EH EFI: electric start with 12 amp charging.

15MH EFI: same weight, 15 hp, for boats or waters limited to 15.

25MH EFI: the next step up in power.

See the range in our Mercury 20 HP outboard motors section and main Mercury outboard motors category.

Mercury 20 HP EFI 20MH outboard motor for sale: price and worldwide shipping

The current price of the Mercury 20 HP EFI 20MH outboard motor is shown at the top of this page. You can add it to your cart and check out straight away, or if you’d rather talk to a person first, send us a message through our contact page and we’ll come back to you with a full delivered price to your country.

What you get

• Mercury 20 HP EFI 20MH outboard motor, new
• 3.2 gallon fuel tank and quick connect fuel line
• 3 blade aluminum propeller, fitted
• Owner's manual
• Mercury Marine 3 year factory warranty from the date of purchase

Shipping worldwide

We ship to buyers all over the world. Every motor is packed securely for the journey and sent by courier, freight or sea depending on its size and where you are, with tracking from dispatch to delivery. Import duty and local taxes depend on your country, and we’re happy to explain what to expect before you pay so there are no surprises.

Buying with confidence

Have a read of our refund and return policy, see what other boat owners have said on our customer reviews page, and find out more about who we are on the about page.

Mercury 20 HP EFI 20MH outboard motor FAQ

Does the Mercury 20 HP EFI 20MH outboard motor need a battery?

No, the EFI runs from the pull start.

How heavy is it?

About 103 pounds.

What shaft length?

15 inches, short shaft.

Is it new?

Yes, with the Mercury factory warranty.

Do you ship worldwide?

Yes. Contact us for a delivered quote.

Order your Mercury 20 HP EFI 20MH outboard motor

Twenty horsepower, fuel injection and no battery, in a motor two people can still lift. Add the Mercury 20 HP EFI 20MH outboard motor to your cart now, or send us a question first. You can also compare it with the rest of our outboard motors for sale.