Review: Mercury EFI 40ELPT outboard

By: Andrew Norton

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  • Trade-A-Boat

The light Mercury EFI 40 four-stroke outboard motor suits tinnies down to 4.4m.

Review: Mercury EFI 40ELPT outboard
The Mercury EFI 40 four-stroke outboard motor is lighter than some comparable DFI two-stroke outboards in its power range.

Originally published in TrailerBoat #253, February / March 2010

Using the powerhead from a Yamaha F40F outboard, the Mercury EFI 40 four-stroke outboard motor is lighter than some DFI two-stroke engines in its power range. However, it still develops plenty of torque. Of the other low-emission 40hp outboards, only the Yamaha F40F and Tohatsu DFI TLDI 40 outboards are lighter.



Available in both standard and Bigfoot gearcase models — the latter having a 2.33:1 gear ratio and intended for workboats and houseboats — the Mercury EFI 40 outboard motor has a relatively simple (for a four-stroke) three-cylinder powerhead with six valves actuated by a single overhead cam. Although the cam is belt-driven the engine is a non-interference type so that should the belt break the valves won’t contact the piston crowns. The same pistons and conrods are also used in the four-cylinder four-stroke Merc 50 and 60, so spares should be readily available in remote regions.

The multipoint fuel injection provides true turnkey starting hot or cold and ensures air/fuel ratios stay constant regardless of barometric pressure or altitude. The engine runs as well on alpine lakes as it does at sea level , whereas its three-carbie counterpart needs re-jetting if used for extended periods at higher altitudes. This also requires occasional carbie balancing and is a finicky task using vacuum gauges. Yet the EFI 40 weighs only 2kg more than the carbie engine.

EFI simplifies diagnosing running problems and this is done using a plug-in laptop computer. It also gives dealers an indication of engine mistreatment, which of course could affect the warranty coverage!



Mounted on a Savage 435 Jabiru Pro vee-noser the demo Mercury 40 EFI was well matched to this hull and had sufficient midrange torque to overcome the inherently stern-heavy nature of this hull when a low-emission 40hp outboard is fitted. The Mercury EFI 40 was still 17 per cent lighter than the maximum outboard-weight rating.

The engine started instantly hot or cold and warmed quickly from the latter. No oil smoke appeared at any time and providing the anti-ventilation plate was kept at least three-quarters immersed power astern was good and no cooling-water starvation occurred. However, the standard Mercury side-mount remote-control box was stiff in its action (a common complaint) and Mercury needs to redesign the control-cable operation.

Pushing 570kg, including two adults, and spinning a 13in alloy prop the EFI 40 trolled us at 5.2kmh (2.8kts) and 750rpm using 0.6lt/h with scarcely any vibration through the hull structure. A clean plane was achieved at 24.2kmh (13kts) and 3500rpm with the passenger sitting forward of amidships to help trim the hull.

At 4000rpm the averages were 33.8kmh (18.2kts) and 5.5lt/h, and through a full-lock figure of eight turns at this rpm no prop ventilation occurred. WOT averages were 56.4kmh (30.4kts) and 12.5lt/h at 6000rpm where we could talk normally at the helm. Only Yamaha’s F40F is as quiet at WOT and none of the other 40hp low-emission engines are this unobtrusive!



Because of the swept-up lower cowl lip, powerhead access is not as good as the F40F, but the oil dipstick, oil filler cap and canister oil filter are still easily reached.

Mercury recommends servicing the EFI 40 every 100 hours, or annually (also for waterpump impeller replacement) after the initial 20-hour service. However, I would also change the engine oil and filter every 50 hours if doing extended trolling, where, due to the engine running relatively cold, there’s piston ring blow-by of unburnt fuel leading to dilution of the sump oil. The cam belt should last at least 800 hours before replacing.

Providing the EFI 40 is maintained by a Mercury Authorised Service Centre at recommended intervals the recreational-usage warranty coverage is five years. The EFI 40 has an OEDA 3 Star exhaust rating.



Engine type

Crossflow SOHC four-stroke outboard motor


3 in-line/6

Prop HP at RPM

40.1 at 5750

WOT rpm range

5500 to 6000

Piston displacement


Bore x stroke (mm

65 x 75

Ignition system

Digital inductive w/ electronic advance

Charging circuit

18amp w/ voltage regulation

Break-in period

10 hours

Fuel type


Fuel capacity

Fuel tank not supplied

Oil type

Quicksilver SAE 10W30

Oil capacity

2.0lt sump

Gear ratio


Transom height




Rec. retail price


Spare alloy prop


Servicing costs*

Year one $381; Year two etc. $239

*As per manufacturer’s recommended schedule excluding parts. All prices current as of November 2009. Demo EFI 40 from Hastings Marine, Port Macquarie, NSW, phone (02) 6583 5511. Prop and servicing prices from Lifestyle Marine, Toronto, NSW, phone (02) 4959 1444.


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Originally published in TrailerBoat #253, February / March 2010


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