Yamaha 115 engine problem won't go!

[oc48]

I have a Yamaha 115 2 stroke. It has run perfect for 4 years! Now, it idles fine (although it seems to idle a little faster than it use to) and the reverse works fine. However, when I hammer the throttle, it only gets about 2500 rpms and will not get on plane.

I was thinking a fuel filter but after reading here, it might be a carb problem?

Any thoughts?

[jb123]

most probable, if it has sat for any length, probably gummed up. best to break them down, soak and get them all cleaned up, replacing any worn parts.

[Hamfisted]

How old is the fuel filter? Are you using a Racor fuel/water separator? If not, you should. But it does sound fuel related. You can pull the main jets out of the carb bowls and inspect 'em for any clogging or debris. Get some Berryman's Chemtool spray (Walmart) and spray it up into the carb bowls through the main jet orifice where you pulled the main jet out of each bowl. Inspect the O-ring seal on each main jet for tears or cracks and replace as needed (dealer item). How old is the fuel pump? If it's more than 5 years old replace it. There's only one there and if it craps out you are SOL. If you don't have one already go to www.YamahaPubs.com and order yourself a service manual for your motor. It'll explain all the procedures needed. Good luck.


Mike......... Miami, FL

[oc48]

Yea I need to learn how to work on this myself. I actually took it to the shop yesterday so I'm waiting on an estimate.

I'm still using the original fuel filter. My boat doesn't ever sit for longer than 2 weeks. As a minimum, I get out and fish at least once each 2 weeks.

I boat the boat new in 2001 and the only thing I've ever had to change is the impeller (spelling?). Other than that, everything is still factory original.

I'm hoping the shop doesn't kill me, but that 80/hour labor rate already sounds expensive!

[oc48]

man I feel like an idiot. They say the spark plugs were bad. Can't believe I just didn't replace them. They also said I had a carb giving too much gas. They are going to rebuild the carb. I guess that's what I get for being an idiot. $315 bucks.

[Ken]

OC,
Don't be too hard on yourself - it's not an easy job keeping outboards running at their peak.
A lot of knowledge comes from experience, or learning "the hard way".
Get yourself a Yamaha shop manual and owners manual - read all the way thru the owners manual.
Set yourself up a schedule of maintenance for your outboard. You need to do, on an annual basis (minimum), spark plugs, lower unit oil, shock treatment with a fuel detergent, lube, and others the owners manual may list.
The best way to keep those carbs from gumming up again is to run the motor at least once a week, even if it is just with the earmuffs and garden hose. If this is not practical, then follow the procedure in the owners manual for storage: fogging, fuel stabilizer, etc.
In addition to a shock treatment once a year, or more often if you run more than 100 hrs/year, is to add a detergent to the fuel every so often.
I run a can of Seafoam (16 oz) to 16 gal on fuel every third 16 gallons. This helps clean the fuel system of gum and varnish, and keeps carbon build up at bay.
Just consider that $315 part of your learning experience - Outboard Motor Maintenance 101 .
Good luck,
Ken K