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I bought a Yamaha 25 hp autolube from 1988. From the beginning I have this motor it goes into the limp mode (with flashing of RED light) after I open to full throttle for a while.
This is what I have done trying to solve the problem:
1) Oil level is ok and tell-tale pumps a lot of water
2) Run on premix to exclude an oil problem
3) Change the sparks
4) I checked the thermostat, but it’s fully open about 80 C
5) I checked the T sensor. Not closed at 100 C. when heating with a lighter the resistance becomes zero
6) Then I decide to pull the head and the exhaust cover, cleaned everything as much as possible. Wasn’t so bad (no salt water use). But, I found two pieces of the impeller, stuck into the outflow holes of the water jacked. So, thought this should be the cause. To be sure a replaced the impeller. However, the one which was installed was complete, so the parts should be from a previous one. Flushed everything (also water pipe towards head) with compressed air.
After this I build everything together with new gaskets. Unfortunately, I still have the same problem unless the head is now much cooler (felt with my hand). Cylinder walls are warmer the head.
So, at 50% power, it runs for hours. But opening to full throttle, the motor falls after about 1000 meter into the limp mode (lower rpm) and the red led flashes. The tell tale sprays constant water at full throttle. After falling into the limp mode, the motor accelerate after a few seconds till the same story happens again.
What should be the cause? Have I missed a piece of the broken impeller, (somewhere in the space in the head where the water pipe from the pump ends. This part wasn’t visible.
Thanks in advance for your answers.
This is what I have done trying to solve the problem:
1) Oil level is ok and tell-tale pumps a lot of water
2) Run on premix to exclude an oil problem
3) Change the sparks
4) I checked the thermostat, but it’s fully open about 80 C
5) I checked the T sensor. Not closed at 100 C. when heating with a lighter the resistance becomes zero
6) Then I decide to pull the head and the exhaust cover, cleaned everything as much as possible. Wasn’t so bad (no salt water use). But, I found two pieces of the impeller, stuck into the outflow holes of the water jacked. So, thought this should be the cause. To be sure a replaced the impeller. However, the one which was installed was complete, so the parts should be from a previous one. Flushed everything (also water pipe towards head) with compressed air.
After this I build everything together with new gaskets. Unfortunately, I still have the same problem unless the head is now much cooler (felt with my hand). Cylinder walls are warmer the head.
So, at 50% power, it runs for hours. But opening to full throttle, the motor falls after about 1000 meter into the limp mode (lower rpm) and the red led flashes. The tell tale sprays constant water at full throttle. After falling into the limp mode, the motor accelerate after a few seconds till the same story happens again.
What should be the cause? Have I missed a piece of the broken impeller, (somewhere in the space in the head where the water pipe from the pump ends. This part wasn’t visible.
Thanks in advance for your answers.