I'm not sure the year the 6 cylinder # is 6515548. Anyway I bought the boat a month ago and I cant get the engine to go ant faster than 10mph. The engine hesitates like it wants to go but it does'nt. I've brought it to the shop they cleaned the carbs as well as rebuilt the fuel pump, checked the compression and spark but the problem is still there. It's not like the fuel is'nt getting there because it is eatting gas at a fast rate. Please help!!! 