My 90s mariner 15 hp starts and runs ok up to 75% power then just starts revving as if in neutral if i try to go any faster any help would be appreciated as i am new to boating. Cheers
Sounds like prop hub is slipping. Make a mark on prop nut and prop, having marks lined up with each other. Go for a test run, if marks don't stay lined up, hub is slipping.
Prop would need to be rehubbed or you could get a new prop
