89 Yamaha 9.9 4 Stroke Help

[martin93662]

Hello...recently my 1989 yamaha 9.9 4 stroke is stalling after a couple of minutes trolling on the lake. After my first experience with this problem, I changed out the spark plugs, cleaned out the fuel filter, and checked the fuel lines for obstructions. As well, I always make sure to use clean gas. The engine fires up on the first or second pull with no problem. However, the problem still remains with trying to troll at low speed. The engine cuts out as if it is not getting enough gas. I bought the boat in June of 06 and spent about $400.00 to have the carb rebilt. Ever since then I have had no problems with the engine until now. I do the oil changes and lower unit twice a year myself. Any suggestions/solutions???

Thanks
Martin93662

 

[64FAIRLANESC]

Re: 89 Yamaha 9.9 4 Stroke Help

I would like to know if you live up north or down south. If the motor is sitting over the winter months without proper winterization being done you can clog the carbs up very quickly.

Mercury makes a product called quick clean that work very good at keeping the fuel system clean and or helping one that has problems already. It costs $10-$20 depending on where you live but only takes a small amount to treat several gallons of gas.

We just got a new product at our marina that brought a 150Hp Optimax back from running rough. I will check the name and post it at a later date.

Any information on how long the boat sits idol would be helpfull.

 

[martin93662]

Re: 89 Yamaha 9.9 4 Stroke Help

Thanks for your reply. I live in central California and when I do use it, I boat at Millerton Lake, Pine Flat and the Kings River . I never let the engine sit for longer than one month. During the months that I do not use the boat, I will fire up the engine just to make sure that the gas runs through the motor and the seals are moist, per the info given to me at the boat shop where the service was done on the carb rebuild. As for winterization, because I do fire it up once a month, I have never done any kind of winterization maintenance other than changing the oil and lower unit and now just recently, the spark plugs. Let me know if you need any further information. Thanks so much.
Martin93662

 

[martin93662]

Re: 89 Yamaha 9.9 4 Stroke Help

Moving Up...

 

[gss036]

Re: 89 Yamaha 9.9 4 Stroke Help

Check to see if there is a fuel bowl drain on the carb, drain it out into a clear glass jar if possible to see if there is junk in it. Maybe change fuel filter if there is. Also might want to run with SeaFoam in the gas. That stuff really works and it is becoming so popular that most parts houses are raising the prices.

 

[sdsaw]

Re: 89 Yamaha 9.9 4 Stroke Help

Is it stalling at the higher speeds?
I was having a similar problem with mine at the lower RPM trolling speeds.
I ended up finding some carbon build up where the carb butterfly plate seats in the carb bore.

Look to see if you have this same issue.
You can clean it yourself with some carb cleaner and a small nylon bristle brush.

You may also just be in need of a simple adjustment of the pilot screw.

*** They charged you $400 to rebuild the carb on that motor?
I hope they did some other work other than just the rebuild.
That's crazy! Get yourself a "factory workshop manual" and DIY

Scott

PS: Pineflat is a really nice Lake

 

[martin93662]

Re: 89 Yamaha 9.9 4 Stroke Help

Thanks to both gss036 & sdsaw for your replies. I will give both suggestions a go and see what happens, hopefully one of them will take care of the problem.
Thanks again,
Martin93662

 

[steve66]

Re: 89 Yamaha 9.9 4 Stroke Help

Hi Martin,I had the same problem on a small honda and numerous other outboards.The problem every time was a blocked pilot jet.
Regards Steve

 

[martin93662]

Re: 89 Yamaha 9.9 4 Stroke Help

Thank you very much Steve.. I will be checking yours and the other suggestions on my next day off. I appreciate all the help I am getting here.