Yamaha 60 Overheating?

[Paul_Dublin]

Have a pair of 1996 Yam 60’s with strange problem on one.<br />Ran for about 2 hours perfect, and kept revs to no more than 5500-5600. Stopped fine and ran fine on all revs. Came back in to harbour and backed off throttle to idle for a few mins and then moved off again. Power seemed to be right down as if it was not sparking on all cylinders. It seemed to get bogged down and then it would pick up after about 3000rpm.<br />Did this for the next few minutes where it would idle OK, bog down at low revs and then surge forward.<br /><br />Next day, ran perfectly all day again, but just as we were heading back the same motor seemed to be down a bit on power. Would only get about 5200revs where I had to back off before to stop it getting more than 5500 (It reached 5800 for a few seconds once).<br /><br />Carbs were recently cleaned and cooling seems to be fine on the motor (telltale is good and water coming out all the right places).<br />I would assume the fuel pump either works or not, so wouldn’t just cure itself after a nights sleep.<br /><br />Is there anything that would cause this loss of power at low revs and then surging?<br /><br />Is it possible the motor thinks it’s overheating?<br /><br />What should I look out for?

 

[ivar]

Re: Yamaha 60 Overheating?

Sounds like a fuel restriction, at higher rpms the fuel pump overcomes the resistance and provides enough fuel.

 

[Paul_Dublin]

Re: Yamaha 60 Overheating?

Ran it again tonight. <br />Is now OK at low revs, but completely lacking power. Acting as if not getting spark in one of the cylinders.<br />Where could the feul restriction be? I checked the lines and even pumped the ball while under power with no effect.<br /><br />Checked this on dry land and it is getting sparks. <br />Could there be any type of intermittent fault with ignition? <br />What else should I look out for?

 

[ivar]

Re: Yamaha 60 Overheating?

I have a 92 Yam 60 , it have been submerged in saltwater twice. I occasionally have some problems like the one you describe in your last post. <br />Make sure your plug caps, plug leads and electrical conditions on the coils are in good condition, clean the ground connection to the coils. I had one coil fail on me , but that acted completely different , it was only when it was hot and only over 4000 rpm. <br /><br />How does the plugs look? Are all the same or is one of them more white or black than the others? <br />If one plug is either dry or dripping with gasoline , I have experienced that the float in one of the carbs have a tendency to stick. Either giving no gas or flooding.

 

[Paul_Dublin]

Re: Yamaha 60 Overheating?

Checked tonight. The sparks are all the same. Not dry, but not dripping either.<br />The cables to the coils are in perfect condition and the plug leads seem to be in good condition<br /><br />I checked for spark and they are all sparking although I don't know if there is such thing as a weak spark or strong spark.<br /><br />final test is to check the Compression, and then possibly swop carbs from the identical motor.<br /><br />Still get the feeling it's not firing on all cylinders though.<br />Is there any conclusive way of testing under power?

 

[Paul_Dublin]

Re: Yamaha 60 Overheating?

Seemed to sort out problem with a stripdown of the carbs... And lots of blowing.<br /><br />There seemed to be something blocking one of the jets and some "sugar" on the lower carb bowl. Must have seawater in fuel.<br />She's running good now.

 

[ivar]

Re: Yamaha 60 Overheating?

Nice to hear you got it sorted out. Those carbs can be a real b!tch to get completely cleaned sometimes. <br />(And according to what I've read on this forum , on some Yamaha carbs, sometimes the debris gets stuck so bad its almost impossible to get out of the tiny passages)