Carb metering jet size on 200HP Yamaha

[oldfisherman]

I have a 1996 200HP Yamaha and while cleaning the carbs noticed that one carb had a #158 size jet while the other side and the other two carbs all have #154 size jets. Does this create any particular problems? I bought the motor/boat used a year and half ago and have not noticed or had any problems that I could attribute to this jet size difference. Carbs are being cleaned as they had some water and and junk in them even with the filter and a fuel/water separator. Does the isopropyl alcohol based water absorbing additives added to the fuel tank cause jelling of the fuel in the carbs? I drained and dried the fuel tank back in Feb and have detected water in the fuel again. Any comments on this? Thanks.

[Ken]

oldfisherman,
I would get myself a Yamaha shop manual for that particular model outboard - should say in there what jet sizes to use.
Sounds like that fuel/water separator is not doing its job - I would install a different kind - try a Racor see-thru.
I would stop buying my fuel from where ever you have been buying it - sounds like you are getting contaminated fuel at the pump.
No, fuel stabilizer like Sta-Bil or Seafoam will not cause gelling of the fuel in the carbs - letting the outboard sit up for months at a time w/o being run will do it though - try to run the motor at least once a week - even in the off season, and even if it is just with the earmuffs and garden hose.
Good luck,
Ken K

[Hamfisted]

What Ken says.

You'll find in the factory service manual that some motors had 158 on one side and 154 on the other, or that both sides had 154's. Just make sure the O-ring seals are in good shape on the main jets. Any cracks or distortions will result in flooding. Go to www.YamahaPubs.com and order yourself a service manual.


Mike

[Hammer]

You can go to Yamaha's Online parts http://www.yamaha-motor.com/outboard/parts/home.aspx to see which size jets are in each carb. The Starboard S (right) side may be the same for all carbs and the Port P (left) side may be different per carb. My carbs had a S and P stamped on the top of the cards as a ref.

[oldfisherman]

Appreciate all the replies concerning the carb jet sizes/water problem as it answered my questions. Since the engine runs good, I won't muck with the jets. As far as the water in the fuel, guess that when I filled the tank (126 gallons) before Hurricane Dennis, the service station's in-ground tanks were almost empty and I may have picked up some water at that time. I have replaced the fuel/water separator and emptied about a half-cup of water out of the old filter separator when it was replaced. I added a fuel additive to the tank and will continue to monitor the filters/etc for water. Again, thanks to all who replied. This forum sure is a good place to get useful info on Yamahas from those more knowlegable and experienced individuals.

[tripleb]

Hello oldfisherman,

I also got a bad batch of gas in the same manner with Dennis. Fortunately, the gas was for my generator which cause the unit to "miss". It did continue to run through the first tank, I added some SeaFoam to the second tank to displace any remaining water. Problem solved.