Yamaha 15hp 2-stroke wont idle

[MicHughV]

I've gone thru' this ordeal on numerous occasions.
I have used every over-the-counter carb cleaner ever made, compressed air, etc, but still no go.

In frustration I take the carb (in pieces) to a local outboard repair shop. There they place all the pieces in a basket and soak it overnight in some propriety solution they have in a big 40 gallon drum.

The next day, I give them $25 and take the pieces back, re-assemble them and put it back on the engine.
Voila, starts and runs like new. Worth every dime of the $25 as far as I'm concerned.

I have no idea what is in this magic vat, but time and time again, I have availed myself to this service, and every time it has done the trick.

[Tspringer]

Originally Posted by Cheechako

I had this same issue. Does it vibrate more than usual when you try to reach higher rpm? It was a main bearing on mine. Wouldn't rev up or idle well after being perfect for years.... I kept trying to solve the "fuel issue..."
Fortunately a cruiser in the same yard as me in Trinidad was an ex outboard mechanic, new just what to do. Took us about 1.5 hours to replace the bearings.

This could be what is going on. I have noticed some different and strange sounds but nothing that sounded terminal in any way.

Still, the more I think about it the more I think this makes sense, and could be the root issue.

The bottom line is we cannot be a rowboat for three weeks while I wait on parts so there really is no choice but to start trying to find another engine here in the Bahamas.

[MicHughV]

One last thing you could try...somewhere on the carb is a tiny screen mesh, no bigger than this "O". It's often very hard to discern as it gets clogged with stuff. It is positioned in an indentation, and when clogged up looks just like part of the carb body. If you didn't know about it, you wouldn't even know its there.

Also, try this vid

https://www.youtube.com/watch?v=ye_Ui9D8dBE

[malbert73]

Hmm- feeling really good about having an EFI Tohatsu 15 which only weighs 15ish lbs more than an enduro
But hope you figure this out soon. I would completely do the same thing- buy some extra carbs

[MicHughV]

I think Yamaha's are about as reliable as they can get...ethanol laced fuel can cause a problem for them and most any engine...plus a two stroke has oil in the fuel...these things can clog up the tiniest opening....it can be a pain in the rear end...but I've owned several Yamaha's without a lick of problems, other than the occasional carb gumming up, usually only after the engine has been unused for a while. A have a little 8 hp Yammie two stroke that is a jewel, that I wouldn't trade for anything.

[Tspringer]

So now trying to decide whether to buy a new Yamaha 15hp 2-stroke in Nassau for about $2400 or get a 5hp for less than half that and keep it as a backup once I rebuild the old enduro.

[MicHughV]

When you say buying " new" in Nassau I'd check the manufacturer year made stamped on it before forking over yer dough...'jes sayin'......

[malbert73]

Having run a 15 Hp 4 stroke Tohatsu electronic fuel injection for 5 years now, I do think the “enduro dogma” should be challenged. 2 stroke enduros are superb engines. I personally run a 1992 Yamaha C85 on a Boston Whaler and it’s super robust and reliable. It’s basically a large enduro.

But… carburetor technology is old school and inherently less reliable than fuel injection at this point. No cars use that anymore.
the new 4 strokes approach the 2 strokes in weight. My Tohatsu weighs 95 lbs compared to 82 lbs for the enduro. Not that different.

I’ve had mine for 5 seasons. It sits uncovered out in the marine environment and weather for 7 months out of the year on my dinghy in davits.

In those 5 years, it’s been 100% reliable. Only work I’ve done is preventive- an annual off-season oil change and lower unit oil change. I changed spark plugs and impeller this off-season. That’s it. No carb jets, finicky stuff. No mixing oil in gasoline. Nada.

And, it’s quieter and stinks less. Much more eco friendly. Best of all it’s super smooth and quiet at low RPMs so for the inevitable harbor runs in 6kt zones, a lot quieter than a 4 stroke.

So, I’m not sure why you would buy old tech if you’re buying a new OB

[team karst]

Originally Posted by Tspringer

So now trying to decide whether to buy a new Yamaha 15hp 2-stroke in Nassau for about $2400 or get a 5hp for less than half that and keep it as a backup once I rebuild the old enduro.

What? Cant give up now, too many people watching. How do both plugs look?

[Tspringer]

Originally Posted by malbert73

Having run a 15 Hp 4 stroke Tohatsu electronic fuel injection for 5 years now, I do think the “enduro dogma” should be challenged. 2 stroke enduros are superb engines. I personally run a 1992 Yamaha C85 on a Boston Whaler and it’s super robust and reliable. It’s basically a large enduro.

But… carburetor technology is old school and inherently less reliable than fuel injection at this point. No cars use that anymore.
the new 4 strokes approach the 2 strokes in weight. My Tohatsu weighs 95 lbs compared to 82 lbs for the enduro. Not that different.

I’ve had mine for 5 seasons. It sits uncovered out in the marine environment and weather for 7 months out of the year on my dinghy in davits.

In those 5 years, it’s been 100% reliable. Only work I’ve done is preventive- an annual off-season oil change and lower unit oil change. I changed spark plugs and impeller this off-season. That’s it. No carb jets, finicky stuff. No mixing oil in gasoline. Nada.

And, it’s quieter and stinks less. Much more eco friendly. Best of all it’s super smooth and quiet at low RPMs so for the inevitable harbor runs in 6kt zones, a lot quieter than a 4 stroke.

So, I’m not sure why you would buy old tech if you’re buying a new OB

Costs is one factor. I can buy the 5hp Mercury for under $1,400. I can then totally rebuild the Enduro for about $600. Will likely take me a day in labor but I dont mind doing that sort of work. So for $2K -- good bit less than a new Tohatsu, I will have a new tiny 5hp Mercury AND a freshly rebuilt Yamaha 15hp Enduro.

Having options and a backup has a lot of appeal to me.

[MicHughV]

Not to sure about your Mercury decision.....I'd stick with Yamaha...just for the reliability factor...

[Wayne Gilham]

My answer for cleaning out hidden passages in small outboard carbs, is to immerse the taken-apart parts in hot, hot, HOT water with a drop or two of detergent, in Harbor Freight's "Ultrasonic cleaner" (see: https://www.harborfreight.com/25-lit...ner-63256.html) , and run four eight-minute cycles. ALWAYS cleans out every passage! Best eighty buck tool I own for the requirement. Regrets, the forty-buck ultrasonic jewelry cleaners on Amazon don't have big enough chamber... (Sure beats the Original Poster's solution of having several carbs onboard!)

[malbert73]

Originally Posted by Tspringer

Costs is one factor. I can buy the 5hp Mercury for under $1,400. I can then totally rebuild the Enduro for about $600. Will likely take me a day in labor but I dont mind doing that sort of work. So for $2K -- good bit less than a new Tohatsu, I will have a new tiny 5hp Mercury AND a freshly rebuilt Yamaha 15hp Enduro.



Having options and a backup has a lot of appeal to me.

Reasonable choice for you I think. I forget which kind of dinghy you have but if me I’d try to save money and weight and get a 3.3 hp instead. I used to have a 5hp and sold it because it didn’t plane any dinghy and was much heavier than my 100% reliable 3.3 which is more than enough power as a slow speed backup.
Ie 5 hp is sort of a “tweener” power for RIBs.


And yes I suppose your plan saves over a 3K new Tohatsu.

My point is for others- as yes the Enduro is super rugged but not necessarily as maintenance free as some would think with old tech carb. I am a convert to EFI after initial skepticism.

[Lake-Effect]

Thanks all for tips etc. Some related outboard notes:

- our 1983 Suzuki 5hp 2 stroke soldiers on. I've removed and cleaned the carb a couple of times as a maintenance item, but it was never too bad. This year I bravely removed a brass screw and poked the jet under there. I think the idle is now better but will test and adjust the mix next week.
- I've been a zealot for ethanol-free gas in my little engines, and I was able to buy it at (Canadian) Shell stations because the top-grade was ethanol-free... but this spring I notice that the stickers on the pump have changed, and no longer make that claim. So I need another source now.
- for fun I looked up what a new carb would cost for our ancient motor... it was like US$500

[MicHughV]

My first ever outboard engine was a 2 hp, 2 stroke Suzuki, followed by a 15 hp, 2 stroke Suzuki, both bought in the B'mas. They both ran like a Swiss watch, never once requiring any maintenance, service, etc. This was followed by an 8 hp, 2 stroke Yamaha, probably my favorite engine of all time, also purchased in the B'mas.
I think fuel is often the culprit, may be worth it to have a fine mesh fuel filter on top of the tank when filling up.