Yamaha 115 etxf - weird ??? happenings

[flounderman]

In August motor ran like a champ,new fuel pump & carb rebuild. I use Stabil. This weekend motor would not run for *#@$. Went thru carbs again, still runs like *#@$. Will not idle, just runs rough, seems like a miss, or ???. #1 plug is dry black soot, others are okay. Did a compression check-- # 1=102, #2=105, #3=105, #4=112. When doing #4 test, motor cycles a couple of times and starter disengages, but not on other cylinders. Others will cycle for a ten count. Also a tinney sound from motor when doing #4. Do not have stuff for a leak down test. Any ideas?

 

[rodbolt]

Re: Yamaha 115 etxf - weird ??? happenings

check the new fuel pump, test spark, clean the carbs again.
the dry soot indicates that cylinder is rich.

 

[flounderman]

Re: Yamaha 115 etxf - weird ??? happenings

Hey thanks Rodbolt, I just re-did the carbs again--good cleaning, checked floats, re-installed carbs, still runs like #%$@. I have to buy a spark tester, I will do that in a day or two. What is your idea on the pump? Maybe a bad diaphram?? #1 plug is still sooty. Thanks Jerry