I have tried reading most faqs and other posts to try and figure this out on my own but still stumped. I just got this 1973 delta tri hull with a 140hp merc I/O in it. The engine will idle very well and has decent to good power at low rpms <1700. The problem is when i put the hammer down it doe not move at all like a 140 hp on a 17ft er. maybe 15mph maybe a little faster. First tried the obvious problems like plugs, fuel filter, some spray carb cleaner, new coil, the prop has a few very small nicks in it, but the rubber insulator is intact, eg when i put it in gear and try to turn it by had, it just moves the engine. my question is what problem could i have, because the engine is doing 4200-4300 rpms just fine, no sputtering or poping etc. but the boat wont really plane out or move well. Id appreciate any help.
