Direct fuel injection was supposed to be the "savior of the two-stroke outboard" when it came to fuel economy and marine EPA exhaust regulations. Sure, you get great fuel economy, no smoke and zero emissions when the engine isn't installed on the boat anymore... At least, that is what some manufacturers were selling in the early 2000's. However, a direct injection doesn't solve sloppy engineering. Instead of harvesting the power, via smoother engines, more efficient designs, and balanced materials versus forces, many engines simply turned into smoking heaps, and reduced emissions as they sat on the docks. Far too many boaters were stunned by an epidemic amongst marine engines. So many marine 2-stroke direct injection motors fouled early on, smoked their whole lives, or even self-destructed that stories are routine.
Since this stigma is not what the motor makers had in mind when they invested all that cash into marine motor Research and Development, at least two other major outboard manufacturers are now making a reasonable effort to stem the plague. Better materials, better engineering, and better design no longer cripple these marine engines (and the manufacturer's reputations). Then there is Yamaha, these marine motors come with impressive two-stroke technology. Since the 2000 model year these engines have consistently put out top power, efficiently, and it's all based around direct fuel injection. More about Yamaha marine Two Stroke Fuel Injection
Compared to conventional carburetion, direct fuel injection (DI) is more than merely an alternative method of getting fuel into the mariner's engine. In carbureted two-stroke motors, the fuel and oil mixture enters the cylinder from the bottom of the piston. The mixture travels up and around the piston skirt to reach the top piston ring. Because the oil is thinned by fuel, enough oil passes around the bottom ring to move up and lubricate the top piston ring. More info about marine Two Stroke Fuel Injection