2005 yamaha 2 stroke 90 problem

[petreaux1]

Can lower unit cause engine damage? This morning my motor seemed like it had a miss, a real severe, all of a sudden miss. I was out on lake and it wouldnt go in gear without killing and was running very rough. Then it wouldn't even run unless idle lever was revved way up; to get home I tilted up, got prop out of water, hit forward gear and got prop spinning revved up, and lowered spinning prop into water and made it 3 miles back to shore. That was the only way to achieve forward progress:get prop in air , high rpm, lower spinning prop into water. Once in gear and revved up it went 30 mph, but as soon as i idled down it killed w/ a nasty buck. It starts right back up but then kills w/ a buck. It seems like the lower unit or driveshaft is binding and killing motor???
Once on trailer seemed like a real bad miss, but then I heard a clanking seems to be coming from lower unit at same instant as "miss". Clank could be coming from powerhead, hard to isolate noise, but with plugs out engine spins freely and sounds normal so it seems crank/pistons are ok?? I drained carbs, changed plugs, motor starts instantly, has 140 psi compression all 3 cylinders, but at anywhere near idle rpms the engine bucks and kills. Even in neutral gear....... it seems like the lower unit is "killing" the engine w/ a clank.???
When I put motor in forward gear, engine off, the propeller will spin forward freely and make click,click,click,click,click sound, like one gear just missing another. Is this correct??? It will not spin freely backwards.
when I put in reverse, engine off, the prop wont spin freely either direction.
Any help will be deeply appreciated .

 

[99yam40]

Re: 2005 yamaha 2 stroke 90 problem

sounds like lean sneeze,Pull and clean carbs pilot jet/passages plugging

 

[rowboater]

Re: 2005 yamaha 2 stroke 90 problem

Could very well be a lean sneeze condition from what you describe but it might be be worth draining the lower unit and checking for any metal or other obvious signs of damage.If nothing else you end up with fresh lower unit oil and a little piece of mind.The prop should spin freely when in neutral,in FWD the prop should not spin freely it should be positively engaged,same with reverse.The prop should engage in different directions depending on whether forward or reverse is selected.It's possible the linkage is out of adjustments not allowing the lower unit to fully engage gears.Lots of info on lean sneezes on the search feature.I had a lean sneeze condition on a 1997 Yamaha 115.In my case the "sneeze" was definetly audible as coming from "back thru" the carb. Rodbolt helped me with some troubleshooting before mine was narrowed down to a bad fuel pump.On a side note sure is a shame he no longer posts here.That was one tech who knew what he was talking about.Seems like pulling and cleaning-rebuilding carbs is a common fix before trying to isolate a problem.Not sure I'd jump to that step so quick.99yam- I mean no disrespect by this just in my experience see this advice offered all to frequently.Not saying that wont be a fix just would advise troubleshooting a little more first. In my " lean sneeze " condition testing the fuel pump,which was very simple,kept me from tearing into a perfectly good carb.Good luck and do us a favor and post what you find as it always helps to learn what fixes stuff.

 

[petreaux1]

Re: 2005 yamaha 2 stroke 90 problem

Thanks , how would I test a fuel pump?

 

[rowboater]

Re: 2005 yamaha 2 stroke 90 problem

Will look in the manual tomorrow but I remember using a vacuum gauge.You applied vacuum to the fuel pump diaphragm and it had to hold for a set time.That's the readers digest condensed version for sure.It would be worth investing in a decent manual.My motor was a 1997 and although probably similar pretty sure there's gonna be some differences in the testing procedure.The manual is also gonna help in doing many maintenance tasks and it will be a big help in getting a better understanding of the motor,gear-case,electical,fuel system,etc.
Here is a link to my problem from years ago

http://forums.iboats.com/showthread.php?t=170843&p=1133393#post1133393

You can from his reply why someone like Rodbolt was so helpful.

 

[Capt Ken]

Re: 2005 yamaha 2 stroke 90 problem

Remove the pump, hold finger over one port while sucking on the other. If you can't pull a vacuum, diaphragm is bad.