Yamaha Oil blending Unit, Any Ideas

[ppidgursky]

Good Day everyone, I have been battling problems with my poor little boat. 1989 Yamaha 50 ELF.
What would happen if the oil blend unit was not working properly?
I would run the boat, cold she start, run, and fly. After about 4 min full thottle, she will cut off, usually followed by the buzzer. Sometimes the buzzer comes on first.
Once she shuts off I have to wait awhile before I can run it again. Once I get it running, it will spit and putter and will sometimes pick back up. But lasts only a min. then dies again. I originally thought carbs, but I have torn down and cleaned a dozen times. After I still could get it I brought to a repair shop. They torn down and cleaned them, they thought they got it, but when I got it back....nothing new.
Have new fuel pump, hose and bulb to tank, plugs, carb rebuild, fuel and batteries, and the reeds checked out OK. Now someone tells me the oil blend could be doing it. Is it possible? The old plugs were fouled when they were replaced. If so, is the only way to test it to disconnect it and premix my fuel?

Please let me know. Any help will be appreciated.

Thank You

 

[Ray Neudecker]

Re: Yamaha Oil blending Unit, Any Ideas

Sounds more like an overheat than carbs to me. The oil warning on that model is based on the anount of oil in the tank. It should not reset the alarm unless oil is added to the tank when alarm goes off.

 

[ppidgursky]

Re: Yamaha Oil blending Unit, Any Ideas

I'm sorry, I thought I mentioned that, the oil tank is full. When I brought it to the shop it had 1/2 tank. The shop thought the same thing and filled it up. So the last time I took it out it had a full tank of oil, and the results were the same.
If the pump was not working properly, would it cause the buzzer to go off and shut off the engine.
You would be go full throttle and would here the rpms drop. Slowly at first then all at once shutting it off.

 

[Ray Neudecker]

Re: Yamaha Oil blending Unit, Any Ideas

If the cause is overheat, then the limiter will kick in and reduce the rpm's to 2000 or so until it cools off. Be sure the anti siphon valve attached to the tank in the boat is not defective also.

 

[ppidgursky]

Re: Yamaha Oil blending Unit, Any Ideas

OK here is another for you. Lets say it is a overheating problem. What could be the cause of it. When the engine is running I am getting a steady stream of water coming from the rear jet. This I believe tells me there is no blockage or problem in the lower unit, correct? And no bloackage in the top unit, correct? Could the thermostate be cause these problems. What else is there? Unless the oil/gas is not right and running hot that way???

 

[Ray Neudecker]

Re: Yamaha Oil blending Unit, Any Ideas

A leaking head gasket, A blockage in the head due to corrosion, a thermostat problem are things which could cause these problems.

 

[ppidgursky]

Re: Yamaha Oil blending Unit, Any Ideas

Well, I heard some disturbing news today. The repair shop called and told me they have removed the head and found that 2 of the 3 cylinders are scared up. Deeply.
They are saying I must get the head bored and the rings replaced. Does this sound right. Is that the process when the cylinder is scared, and would have this been the cause of all my troubles?
We tested the compression and they tested good, but we did test them when the engine was cooled. My problems see to happen when the engine is hot. Could this be it, or am I getting raped, and not even getting dinner first?