I own a 2000 30 hp johnson 2 stroke on a 14 ft crestliner. If the gas tank was not properly vented could that reduce the rpm or speed of the boat. When I remove the cap to fill the tank it is difficult to open and sounds like a vaccuum when I finally get the cap to move. The air is rushing in the tank, I think. The motors max rpm is between 4500-4800. The most I have achieved is 4100. Any advise would help.
