Two Yamahas now, same problem

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ebassett74

Cadet
Joined
Jul 19, 2010
Messages
14
I have a 1992 or so 115 and 150 yamaha motors. One starts to cut out and gain rpm when you are over 3700 rpm. I have removed and cleaned the carbs, checked and replaced spark plug wires but to no avail. The other seems to have a similar problem but it is fine until the motor runs for about 15 minutes. This motor cuts out on the higher end also. This even has the mechanic troubled. Does anyone have any idea why my two engines are doing this? I will answer any questions in detail if someone has a similar problem or a mechanic that has addressed this issue before. Thank you much.
 
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rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Two Yamahas now, same problem

I have addressed issues your monkey hasnt had nightmares about.
can you post pulser coil and charge coil output voltages at the problem RPM and load?
can you post CDI output voltages at the problem RPM and load?
can you post lift pump output pressure at the problem RPM and load?
post those numbers and your problm is solved.
my advice is to find a factory trained Yamaha tech that has the correct dignostic tools and the training to use them.
 
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ebassett74

Cadet
Joined
Jul 19, 2010
Messages
14
Re: Two Yamahas now, same problem

Thank you much for the reply. It ended up being the CDI. That is one part I could have done without replacing.
 
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99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,874
Re: Two Yamahas now, same problem

On both motors?

Testing is always the best way to find the problems instead of trying different thing to see if they help
 
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