94 bayliner jazz runs super slow but motor is running fine.?

[Kenny Hernandez]

Hi I've just replaced all electrical devices and took to a mechanic to fine tune the motor - it seems to be running well. BUT i cannot exceed 10 mph on full throttle.
i am new to marine craft so idk where else to look for issues other than the jet drive and i can't find any detailed info on that. .
is it possible that the jet drive is the problem or do i need a new mechanic . or just a new boat ?
Its a 1994 bayliner jazz 90hp
Any helpful advice is appreciated. Thanks

 

[The Force power]

Welcome to Iboats :welcome:


These were actually Force/Chrysler engines with a Mercury ignition-system.

What are the RPM's At full throttle? if this is around 5000, my suggestion would be to inspect the Jet drive
Post your next question in the Force forum and you'll be exposed to more specific experts

 

[GA_Boater]

It's moved.

 

[The Force power]

Now that you are here, hopefully Redbarron%% will tune in

https://forums.iboats.com/member/501234-redbarron

 

[sajeschwab]

saw that it was a jet drive, its most likely in the gearbox id say, but im not familiar with jet drives all that much

 

[Redbarron%%]

If you are turning basically redline RPM and perhaps hearing a little miss from the rpm limiter you have cavitation or the wear ring is worn or damaged.
If there is something in the pump or the ring and impeller have too much clearance or have groves worn in them this is what will happen.
Also if the ride plate gasket is missing or not sealing it will blow out exhaust into the pump and suck air.
Inspect the pump wear ring and the impeller and look for something in the impeller blades.
You gotta pump a lot of water and no air to move these things.
Cavitation will not load the motor and it will rev easily.