1985 115 Yamaha

[b_toups]

Topic #1
I have a 1985 115 Yamaha that runs perfectly fine for about 15 mins then completely shuts down. Wait 1 or 2 minutes and will start up again and run for another 10 or 15 mins. I have fresh gas, new inline filters, fuel line, bulb and end connectors. Sometimes if I have to slow down, engine will run rough and then kill. Wait one or two minutes then we're back in business. Not sure what else to do. Any suggestions.

Topic #2
I have a 1985 115 Yamaha that runs fine for about 13 minutes and then shuts down. Very little warning. Wait about 3 to 4 minutes, starts up and runs for about 6 minutes, shuts down again. At the suggestion of an Outboard Mechanic I have:
Drained fuel and replaced fuel lines, filters, and connections. Both tanks.
Lower unit was getting water in oil, so I changed water pump and seals in lower unit.
Gasket between motor and lower unit was leaking, changed that and flushed out all water channels.
Changed thermostat gaskets and took out thermostats, South Louisiana, he felt there wasn't a need.
Changed fuel pump.
Test fire and reset spark plugs.
He checked Stator and he feels they are in good shape.
He suggest that I change ignition pack.

Any other thoughts would be appreciated, Thanks.

 

[erniefish]

Re: 1985 115 Yamaha

Does the boat have a permanent tank ? I would check pick up if it does,

 

[boscoe99]

Re: 1985 115 Yamaha

Yes, sounds like a restriction to the fuel supply.

Get a small portable tank and connect it to the motor. Does the problem remain or does it go away? If it goes away then you know for sure the problem is with the fuel supply TO the motor and not with the motor itself.

But, on a 1985 model year motor, when was the last time the fuel pump(s) were replaced? Perhaps yours is getting old and tired and simply can't do the job it once did. Pumps get tired and pick up screens (if the boat has one) can get partially clogged. Between the two perhaps the motor simply cannot get the fuel that it once did and which is needed to run correctly.

 

[crb478]

Re: 1985 115 Yamaha

Sounds fuel related. Make sure it is venting. I take it there are not alarms and it is not overheating. As stated above try a portable tank and see if it runs correctly. If it cuts out on the portable tank, start pumping the primer bulb to rule out the fuel pump as a problem.

 

[b_toups]

Thanks for the replies. This is what I have done since the first post.
Changed water pump and lower unit seals - thought it may be over heating.
Changed the gasket between motor and lower unit - water was leaking through it.
Changed thermostat gaskets and thermostats.
Changed fuel pump.
A Boat mechanic has been telling me what to do. He checked the stators and he said they look good. He suggest the ignition pack. Any thoughts?

 

[99yam40]

find a good Yamaha mechanic that has been trained to work on these motors and has some common since and does the proper things to a motor.
No motor should be run without the proper parts the manufacturer engineered and installed on a motor.
No water cooled motor should have the stats removed and run for more than a short test maybe.

"He checked Stator and he feels they are in good shape"

Did any of this have to do with any proper voltage testing or is he just a feeling type of guy

 

[b_toups]

He is a well respected Outboard mechanic with many years under his belt, way before all the technology of today. Voltage testing was done, but if its right when you bring it to him it will be right when he checks it.

 

[99yam40]

but if its right when you bring it to him it will be right when he checks it.

What does this mean?


A water cooled motors needs the stats in place to regulat the tempature of the motor to burn the fuel properly not just in cold climates but also in warm. too cold and too warm are both a problem.
Stats also cause some back pressure and force water to flow at the proper speed and direction through all parts of the motor.
Without them in proper working order and in place there will be hot spots and cold spots.
Just because he got away with it in the past without motor damage does not mean it is the correct thing to do to the motor