Battery-less EFI: Awesome New Small Outboard Feature

The 15 HP Suzuki on the back of this boat has EFI, even though it doesn't have a battery.

It used to be that all small outboards depended on a carburetor. EFI requires electricity, and since many 15, 20, or 25 horse outboards don’t necessarily have a battery nor an alternator, it was out of the question. Net result? Lower efficiency, harder starting, and the bane of modern day small internal combustion engines, multiple problems stemming from ethanol. Even if you use ethnaol-free gas, over time the carb got gunky.

The 15 HP Suzuki on the back of this boat has EFI, even though it doesn’t have a battery.

Now, most of the major outboard manufacturers are rolling out small-size outboards with battery-less EFI. Yamaha’s latest F25, just introduced a few months ago, incorporates it. Mercury also takes EFI down to the 25-horse level. And Suzuki outboards have it in their models all the way down to a 9.9. Suzuki has been ahead of the curve, when it comes to these small EFI outboards. I got one of the first 15 HP Suzuki battery-less EFI motors to hit the water back in 2012 and it’s been a joy to run. Starts are almost always on the first or second pull, ethanol has become a non-issue, and efficiency is excellent.

Why aren’t all small outboards built with such a system? First off, expense – it simply costs less to bolt on a carburetor. Secondly, there are some design challenges because the EFI system, fuel pump, and some basic computer controls are necessary, and they need to be powered prior to the engine actually running. Normally, the boat’s battery does the trick. But for these engines a magneto makes the power. It requires a crankshaft rotation of 720 degrees (in other words, the crankshaft needs to spin twice) to generate enough juice, and for the ignition timing to identify the piston positioning. Once this is accomplished, the EFI system takes over. And this is why one-pull starts are so common with these little eggbeaters.

Is the difference important enough that it should play a role in your decision-making, when you shop for a small outboard? Heck yes. I’ve owned at least a dozen outboards of 30 horses and under through the years, and only two have had battery-less EFI. These have also been, without question, the two easiest-starting and most reliable ones – by a long shot.