Do follow Gords post. However, I am not sure this wil tell you anything in this instance. So lets get back to some basics. It is always important to cover things in a few steps at a time and to stick to sound principles, or things get messy real quick. So what we know. by the way, if I have anything wrong here, let me know.
revs to max RPM
under no load
Engine revs to 3200RPM loaded. By the way, it doesn't make too big a difference tied up or moving.
2500RPM produces black smoke in large quantities.
I am worried about your aircleaner. This seems like it has got a lot of soot blocking it. Although I note you said you ran the engine with it removed and no difference. I do think it worthwhile following the lead of "is something blocking the intake further in" scenario. Black smoke is a major lack of air to fuel
ratio. That lack of air to fuel
can be over loaded engine or restricted air into the engine. Overloaded can be prop, but not normally hull
being dirty. Dirty hull
will slow you and cost you fuel, but does not load the engine. Hence having the boat tied to the dock
should not be any detrimental affect to the engine load.
I doubt you will see a spray pattern issue by the way. But a spray pattern issue could indeed cause your problem. Especially if you have hgad water
in the system. Water
will explode in the injector tip and it can chip the tip. Certainly check it if you want. But be very careful. What you do is wrap a rag around the injectors to absorb the fuel spray. Only uncover the one injector at a time. It can come out as a fine mist, which by the way, is actually not what they should do and that mist is dangerous to breath. So the rag is to keep that under control in the engine compartment. The spray pattern should not be a dribble or single
squirt either. It needs to be a spray. However, there is one thing you can't test for and that is more important. It is the lift
or break pressure of the injector seat. It has to lift
at a set pressure. A poor spray pattern can be an issue that can cause this problem. However, you would normaly see it when reving the engine under no load. Lets ope in this case I am wrong. Injectors and air filter are the easy parts