Mercury 9.9 two-stroke outboard engine, can it be started in forward gear? What happened?

1, engine carbon deposit is serious. When there is too much carbon deposit in the engine, the gasoline sprayed by the fuel injection head will be absorbed by the carbon deposit during the cold start, which leads to the lean mixture during the cold start and makes it difficult to start.

2. Too much carbon and dirt are deposited in the throttle valve and the surrounding air intake, and the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake, resulting in the mixture being too rich or too thin and abnormal combustion.