15hp Johnson no water on plane

[salmonite]

My Johnson has a good stream out of tell tale at idle and continues to be good when I crank it up in neutral but when I am on plane the water pump starts and stops??? Unclear if its the motor cause it works fine in neutral and lower speeds but unclear if its a engine height issue or what???

 

[TrueNorthist]

Re: 15hp Johnson no water on plane

The waterpump likely needs to be replaced. Model number?

 

[RSchendel]

Re: 15hp Johnson no water on plane

Are you running a short shaft motor on a boat with a transom that requires a long shaft?

 

[salmonite]

Re: 15hp Johnson no water on plane

standard transom and short shaft should be fine, water pump was just replaced

 

[kbait]

Re: 15hp Johnson no water on plane

If the upper watertube grommet is swelled up, that exact scenario can occur (happened to me.. pump nicely at idle, but not over 1/3 throttle). Requires powerhead removal to access.

 

[salmonite]

Re: 15hp Johnson no water on plane

If the upper watertube grommet is swelled up, that exact scenario can occur (happened to me.. pump nicely at idle, but not over 1/3 throttle). Requires powerhead removal to access.

I can give it throttle in neutral and pumps real strong.... Did yours do that as well or did it do the same thing at neutral?

 

[coolbri70]

Re: 15hp Johnson no water on plane

when on plane, where is the cavitation plate in relation to the water? should be at or just below

 

[salmonite]

Re: 15hp Johnson no water on plane

Just under

 

[salmonite]

Re: 15hp Johnson no water on plane

So the marina dismissed the upper water swelling? Said he had to check on my 06 Johnson because he thought at full plane it dumps out the prop... I dont think that's the case on an 06, anyone know if that's true?

 

[the machinist]

Re: 15hp Johnson no water on plane

So your motor is an 06 ? This is the first you mentioned the year. If so, I agree with the marina, rather a new motor to be afflicted with a swollen/deteriorated grommet.

On that late a motor, you might pull the water outlet Ell from the water jacket, (it's near the top). Run the motor in a tank enough to be able to rev it up enough to blow any possible constriction out of the water jacket/Ell connection. I suspect you have some debris inside the water jacket that is floating around & doing an intermittant blockage to the tell tale.

The tell tale water indicator takes it's water out of the system early on, before it cools the motor, so should have nothing to do with exhausting it through the exhast.

 

[kbait]

Re: 15hp Johnson no water on plane

Agree w/machinist above^. If you clean out the indicator feed and it still indicates intermittently, you should investigate further. If that system is clear, the only reason it wouldn't indicate (pee) correctly is if it isn't pumping correctly.. or has an obstruction somewhere. Find out before an overheat event occurs.