Yamaha F80AET not powering up properly help please


Jan 1, 2020
Hello all :)

We were gifted a 90s model Haines Signature Series 550RE with a Yamaha F80AET motor for Christmas from my very generous Dad & finally got her out yesterday but we're having a couple issues and hoping for some direction for us boat newbies please.

When my Dad used the boat he could get her at 50-60 knots, but even at full throttle we could only get a max of 8 knots yesterday with highest RPM around 3500. Felt like she was bogging down, trying hard to go but just not going like she could be & wouldn't level out, bow up, stern down when in gear.

Is there something easy we should be looking at here or anything you would recommend we do please? She did sit unused for a year or two before coming to us, but was fully checked over by my dad prior to bringing it up, and then again by my husband prior to use. We are just at a bit of a loss as to where to look next.

Thanks so much for your time,


Master Chief Petty Officer
Aug 22, 2013
If the motor has sat for a while unused, which seems to be the situation, then I would suspect that the carburetors need to be thoroughly dismantled and cleaned in a heated ultrasonic cleaner.

One test is to mist some gasoline directly into the air intake system when the motor starts to bog down or stops accelerating. If it picks up and runs that is a good indication that the carburetors are not doing their intended job.