yamaha 50hp engine won't go higher that 3000 RPM

[AndyQ]

I was going full throtlle 5500 RPM and drop to 3000 RPM after that it won't go higer that 3000 RPM. I think is that the control cable broke. Did somebody expirece something like similar???

 

[99yam40]

Re: yamaha 50hp engine won't go higher that 3000 RPM

check compression on all cylinders, look at plugs to see what they indicate, check fuel pump for holes, then check to make sure spark is good and timing is staying in spec

If all is good with that then you are having a fuel problem

 

[Thomasbthatsme]

I just got done fixing the very same issue with my 50hp 2-stroke Yamaha. I was having two issues actually. Poor idling and no high rpm. I pulled the carbs and cleaned them and this solved my poor idle issue but still no high rpm. Thinking about it I realized that low oil makes the engine throttle back so I decided to pull the oil level sensor out of the oil tank to simulate low oil and much to my surprise there was no change. This got me tracing out the wiring to the sensor and I discovered the power feed wire to the sensor actually runs around and under the front of the motor to the starter side. As I was pulling on this pink colored wire to trace it out I was surprised to find the end of the wire was corroded and disconnected from the quick-connect that provides the power to the sensor. I spliced the wire back together with a heat shrink connector and now my motor runs like a champ again. I guess the fact that this wire is under the motor where it is likely to get wet is why it corroded and finally just came apart while I was running high rpm on my last trip out. I spent 2 days working on this before finally narrowing it down. I guess I didn't notice the corrosion because this wire was tucked under the main harness connector near the starter.