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Hi all,
I have done a lot of diagnostics with my 1990 90hp Yamaha 3 cylinder 2 stroke so I wanted to see if people had any idea where my issue could lie.
Getting nothing out of the third cylinder right now. First and second cylinder are running. Diagnosed this by taking off the plugs while the motor is running and there’s no change when the third plug boot comes off. Checked fuel pump, and the diaphragm is completely fine. Have changed spark plugs, and switched coil packs and the problem persists in the third cylinder. Compression is at an even 100psi on each cylinder. There is good spark from the spark plug as well. Just took apart the whole third cylinder carburetor and it was clean but I still went through and cleaned everything and the problem persists. Fuel supply to the carbs is also not an issue.
Which leads me to this. I feel as though this has to be electrical and maybe the third cylinder is firing at the wrong time or there’s another issue causing this. If y’all had any input that would be greatly appreciated. Running out of ideas now. With these old two strokes the only real things I’ve learned are fuel, compression, and spark and since it seems that all three of them are fine, I’m thinking timing could be one of my only options. Thanks!
I have done a lot of diagnostics with my 1990 90hp Yamaha 3 cylinder 2 stroke so I wanted to see if people had any idea where my issue could lie.
Getting nothing out of the third cylinder right now. First and second cylinder are running. Diagnosed this by taking off the plugs while the motor is running and there’s no change when the third plug boot comes off. Checked fuel pump, and the diaphragm is completely fine. Have changed spark plugs, and switched coil packs and the problem persists in the third cylinder. Compression is at an even 100psi on each cylinder. There is good spark from the spark plug as well. Just took apart the whole third cylinder carburetor and it was clean but I still went through and cleaned everything and the problem persists. Fuel supply to the carbs is also not an issue.
Which leads me to this. I feel as though this has to be electrical and maybe the third cylinder is firing at the wrong time or there’s another issue causing this. If y’all had any input that would be greatly appreciated. Running out of ideas now. With these old two strokes the only real things I’ve learned are fuel, compression, and spark and since it seems that all three of them are fine, I’m thinking timing could be one of my only options. Thanks!
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