Motor will not run while in the water

[BigAl9663]

I have a 1982 Mercury 115hp outboard that will start and run fine while the motor is tilted up out of the water but will not start when the motor in the water. I can start it out of water but as soon as it is lowered it cuts out. Any ideas?

 

[carholme]

Re: Motor will not run while in the water

If your engine has a s/n above 5594657, the following schematic applies:

http://www.maxrules.com/oldmercs/Wiring/1966ona/37.jpg

Disconnect the Mercury switch and see if it will start in the down position.

Gerry

 

[BigAl9663]

Re: Motor will not run while in the water

Hi Gerry,
Thank you very much for the reply.
I did disconnectthe merc switch but it did not work. It seems to be that there is no gas going to the carbs when in the down posirion.

Alan

 

[GA_Boater]

Re: Motor will not run while in the water

Welcome aboard, Al. Are you running it out of the water very much? The impeller is probably toast.

Is this a new problem?

 

[BigAl9663]

Re: Motor will not run while in the water

Thank you for the hp but the impeller is in great shape. There doesn't seem to be gas flowing when in the down position.

Welcome aboard, Al. Are you running it out of the water very much? The impeller is probably toast.

Is this a new problem?

 

[GA_Boater]

Re: Motor will not run while in the water

I got the impression you were tilting the motor up until it was out of the water. That will do in the impeller is short order if it's run dry.
No problem running on muffs.

Back to the original question - Is this a new problem? Any work done on the motor lately?

 

[Jim Hawkins]

Re: Motor will not run while in the water

How far into the water does the motor sit? Are the rear exhaust ports covered?

 

[BigAl9663]

Re: Motor will not run while in the water

The answer to the original question is, yes this is a new problem and no work has been done to the motor.

The motor was run with muffs and running water a month ago at home with the motor in the raised position, when I brought it out to the lake and lowered the motor the engine would not run. It seems as if there is no gas getting to the motor. When. I brought the boat home I tried running the motor with muffs on and water running but in the down position and the engine would not start. I then raised the motor and then it ran. As it was running, I lowered the motor and it cut out.

I got the impression you were tilting the motor up until it was out of the water. That will do in the impeller is short order if it's run dry.
No problem running on muffs.

Back to the original question - Is this a new problem? Any work done on the motor lately?

 

[GA_Boater]

Re: Motor will not run while in the water

Floats are my first guess.

 

[Jim Hawkins]

Re: Motor will not run while in the water

Floats are my first guess.

+1 (except it was not my first guess)

 

[GA_Boater]

Re: Motor will not run while in the water

+1 (except it was not my first guess)

What was your first guess, Jim?

I'm thinking the floats are hanging up and when the motor is tilted , fuel is getting past the needles because it's not close to vertical. When the motor is dropped the floats are shutting the needles. No gas, no run. Like I said - A guess.

 

[oldman570]

Re: Motor will not run while in the water

You might check the fuel connection at the front of the motor, as it might be worn and sucking air when the motor is tilted down and the weight of the fuel hose pulls on the connection more. When the motor is tilted up the connection will have less weight strain on the connection, and it would seal better and the motor would run. JMO
Oldman570

 

[CharlieB]

Re: Motor will not run while in the water

Oldman makes a good point.

Also very dirty idle passages can restrict fuel flow enough so that once in the water and back pressure on the motor, there simply isn't enough fuel to run and the motor dies.

The carbs need to come off for a proper cleaning. While off install rebuild kits, they are not that expensive for most models. New needles and seats, new gaskets. Proper float adjustments, it should run like new again.