Yamaha 30 DMO running on idle but wont throttle up.

[Cor1982]

Hi Everyone,

I am new here so hi to you all

Yesterday i bought a yamaha 30 PS with problems. i got it now running on idle 3 cylinders cause of a replaced defective spark plug. But when i give it some throttle i sounds like it is choking. I posted a video on youtube : Yamaha 30 DMO 6N3 Choking when using throttle - YouTube

does anyone has any idea's on what the problem could be? i checked the ignition and all 3 cylinders seem to spark but the cylinder on top seems to get a very wet spark plug.


Hope anyone has any idea's

Cheers.

 

[Cor1982]

Re: Yamaha 30 DMO running on idle but wont throttle up.

Today i checked the readings on the pulsar coils, the charge coil and the ignition coils. except the ignition coils all seemed ok. But of the 3 ignition coils 2 gave almost the same reading in ohm and the last one didn't give any reading on the secondary coil... funny thing is that all 3 ignition coils give a spark.... so i donno if this coil could be the cause that my engine is running ok on idle but wont pass the 1500 rpm when i give it some throttle.

Someone said to me that maybe the labyrinth seals in the crankshaft could be defect and that gas/air mixture could flow from one cylinder to another cylinder and could cause the error that is engine is unable to make more rpm than that it is doing now. now my question is. Can a defective labyrinth seal cause this? and is there a good possibility that it is broke?

 

[99yam40]

Re: Yamaha 30 DMO running on idle but wont throttle up.

compression, spark ,and timing are all easy to check.
If ohms are not in spec then test the peak voltage from coils, it is a better test

If all is good then you are left with an improper fuel/air mix to fire properly.
Could be carb problems or air leaks

 

[Cor1982]

Re: Yamaha 30 DMO running on idle but wont throttle up.

Thanx 99yam40 for the advice!

You would not believe what caused the problem... it was the sensor that measures the oil level. when i measured it with a multimeter it didnt make contact but when you hook it up to the cdi it does... so the rpm limiter kicked in preventing it from running normal. on top of things the LED warning light on the front of the engine was broke so you would not notice that the rpm limiter was active.....

End of story engine is just fine and acting as it should only sensor and LED light are malfunctioning. Now i have to figure out if the oil sensor really is broke or oil level is just too low. As for the LED, i think i am gonna buy a new one...

Cheers!