I have had this problem off and on all summer. The Engine seems to be running fine. The boat is used primarily for water skiing, so performance out of the hole is very important. When pulling a water skier, I need to give the boat full throttle on take off out of the hole. The engine between 1200 to 2000 rpms will backfire out of the carb. Once with starts, the engine does not get past this rpm range and sometimes stalls out. If we start slowly bringing the rpms up to 2000, then apply full throttle, the engine operates normally. The engine cannot respond normally with a full thottle start from 1000 rpms without this backfire.

Is this a carb issue?

Also, is there any adjustments I could make on the carb / accelerator pump?

Thanks