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More 2011 6hp Tohatsu questions

jclays

Regular Contributor
My Tohatsu is plagued by stalling. Goes to the shop aprox every 6 months. shop tells me contaminated fuel. Water in the fuel also deposits due to Ethanol. The outboard gets used once a week. It lives on the back on my dingy on the water. I top it off with fresh fuel every use (once a week). Should I run the carb dry after every use? Some have told me not to since I leave it outside on the water. Once the fuel in the bowl evaporates it will leave deposits. Others say run the carb dry to eliminate water in the fuel in the carburetors bowl. Which is it? Also after the last service took the outboard/dingy for a ride. Thirty minutes later she stalled and would not restart. Smelled of gas. Flooded. Fired up the next day like nothing. Took it back to the shop. They checked it out. Ran it in their tank for an hour at various speeds with no issues. Input??
Thanks
Jim
 
Jim,

Always specify precise model, not year, when describing any Tohatsu/Nissan outboard for service. I assume you have an MFS6B.

Always run the carb out at the end of the day. If you know that you will definitely be running tomorrow, skip that as unnecessary... but it still doesn't hurt. If the period of disuse gets to the magic number of days, say about a week, you will start to get noticeable varnishing from fuel evaporation. Think of the deposits in a coffee cup if it is allowed to evaporate -- similar thing.

When you run the carb out, there is only a scant 1/2 teaspoon of fuel remaining in the very bottom, and even if that goes bad, it is only in the bottom of the bowl -- not evaporating from the passages -- and when refilling for the next run, the passages will still be unvarnished. If you want every last drop out, drain it using the drain screw afterward.

If possible, do not run ethanol fuel. Likewise, US fuels start rotting at about 2 weeks, and are noticeably deteriorated at one month. You can slow that by using a good gas stabilizer. In our shop, we like the K-100 products. Ethanol attracts water, and storing the outboard on the water means that your carb and tank vents are exposed to very high humidity, accelerating the rate at which the E gas will get saturated with water. Having the tank vent closed and the carb dry will reduce that a lot.

If using an MFS 4/5/6 with integral tank, bear in mind that if the carb is empty, you need enough gas in the tank to fill the carb bowl by gravity, or you will need to cycle the recoil starter several times to pump the fuel up and into the carb.

If your carb flooded and spilled gas out of the carb vent, odds are that the carb needle got stuck open; Operating the motor subsequently to the event may have freed the stickiness. If the problem recurs, the aluminum body of the needle or the brass seat it runs in may have some corrosion, causing the needle to not ride freely. If so, you will want either a new needle or may need a new carb (if the seat can't be cleaned of corrosion). If you do opt for a new carb, get one for the MFS6A2, as it is a direct replacement, but is designed to an earlier EPA standard, and is less prone to varnishing... and usually gives a smoother idle.

My dinghy has an MFS6, and lives in the water at my boat slip when not used. I run it about once a week, and have had 100% good results by following this regimen. It gets the usual annual service, but that is all.
 
Morning Paul
I have a MFS6C. Friday I purchased a new carb for a MFS6B. Couldn't find a shop with a carb for the A model. Will put it together today.
 
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