Rough running Yahama 115 @ WOT

[coonlake1]

HELP! <br /> My '96 Yahama 115 begins to run rough once at WOT (5500 RPM) but only after a few minutes at that speed. Slowing back to under 3500 RPM for a few minutes seems to reset everything. I can then accelerate back to 5500 rpm, but the roughness comes back again after a few min. <br /><br />Do I have a fuel/carb problem ? This motor has never given me any problems until this began several weeks ago.<br /><br />Thanks for any input!

 

[ivar]

Re: Rough running Yahama 115 @ WOT

Does it lose power also?<br />Have you tried squeezing the primer bulb to see what happens?<br /><br />I have had similar symptoms on my 92 yamaha pro-60 , then it was a coil who crapped out when it got hot. <br />It can also be fuel starvation, check the above post "Yamaha 90 power loss" for more info.

 

[coonlake1]

Re: Rough running Yahama 115 @ WOT

YES, THERE IS A CORRESPONDING LOSS OF POWER WHEN THE ROUGH RUNNING OCCURS. WHICH T/S DIRECTION SHOULD I PROCEEDE WITH FIRST:<br /> 1) FUEL SYSTEM / CARB<br /> 2) ELECTRICAL / ELECTRONIC<br /><br />THANKS FOR THE RESPONSE!

 

[Greg Lawrence]

Re: Rough running Yahama 115 @ WOT

also along with sqeezing the bulb when the problem occurs, run without cap on tank, then try spraying a little premixed gas-oil in a squirt bottle into one carb at a time. if it picks up you can figure out which carb. also if you push in the choke when it bogs, does it pick up? that tells you its running lean and not getting enough gas...

 

[coonlake1]

Re: Rough running Yahama 115 @ WOT

Yes, I have tried choking when engine bogs. This does not improve the situation, and in fact causes a slight increase in the bogging down...that would be normal, would'nt it ?

 

[Forktail]

Re: Rough running Yahama 115 @ WOT

Make sure you're not sucking any water spray into the intake at WOT. Sometimes a depthfinder sender or even a different prop can cause a fine mist of water to get sucked into the intake.<br /><br />It sounds like you're running a rich condition. You may need to clean the gunk out of your carbs and make sure your intake is clear.

 

[coonlake1]

Re: Rough running Yahama 115 @ WOT

Thanks <br /><br /> Last night I pumped my tank using the primer bulb, and I noticed that the seal to the fuel line joint at the motor was dry and cracking. Could that be a factor <br /> I'd imagine that the seals to the fill, vent, and sending unit are in similar shape. Replacing those along with all hoses is my next step.

 

[coonlake1]

Re: Rough running Yahama 115 @ WOT

Ok, I've now:<br />1)pumped out tank. No water or junk in fuel.<br />2)Cleaned pfilters at powerhead, and replaced water separating fuel filter.<br />3)Replaced fuel line hose and primer bulb. Also replaced fuel line to motor fitting. <br />4) Cleaned carbs (With them attached to pwr head) and decarbed engine.<br />5) Engaged choke and pumped primer bulb when engine bogs.<br /><br />...all of the above actions, except item 5, have generally improved the running of the motor, but the bogging at 5500 rpm still occurs after a few minutes at that speed. What's next