Clean Carbs While Running

[anamealreadyinuse]

2012 Tohatsu 20 HP- 4 Stroke.

Is there any additive you'd recommend to run in your gas that will help clean the carbs etc. on a 4 stroke? Ethanol was used in the tank and I think it sat a few months. The motor would not run even at idle unless fully choked. I was able to adjust the idle spring open/shut a few times and broke whatever was gumming it up (I think this is what the problem was) and now it runs but there is a concern it may not be fully solved. Anything I can suggest to run in the gas to clean while it uses up the gas?

 

[Grub54891]

You. Could run some sea foam or similar fuel system cleaner, but if the problem persists, the only cure is to remove the carbs and fully clean then inside and out. You may have got lucky if they keep working......

 

[pvanv]

The bowl of the carb for the MFS 15/20 has a passage in the bottom to feed the accelerator pump (and ABS on motors that are so equipped). That passage can easily get gummed up, and because of that, the carb on these should be drained whenever the motor will sit for a week or longer. I have no clue what an "idle sping" might be, but if you increased the idle stop to keep it running, that may be a start. If the motor will at least run, and if the varnishing is minimal, running might help to clear some passages, especially if there is a solvent (such as acetone or seafoam) in the fuel, but there are a lot of side effects to those solvents. In fact, Tohatsu sells the bowl as a separate piece, because sometimes the passage becomes so clogged and/or corroded that it is beyond cleaning. It's not the absolute best bowl design, but considering the the 20 has been phased-out in favor of the 9.9/15/20 EFI models, the point is moot.

But no, there is no such thing as a "mechanic in a can" that you can add to the fuel that is really effective.

 

[anamealreadyinuse]

Thanks guys...good to know. pvanv what year did they start making the EFI models?

 

[TGuy]

They came out with their 9.9, 15, and 20hp EFI models last summer/fall (2017)

 

[Scott Danforth]

there is no mechanic in a can. fuel system issues usually require physically taking components (such as the carb) apart

 

[jibsail]

I have had a 6hp 4str nissan on my sailboat for over 14yrs .....it did not get allot of use sometimes sat for a month or several months over the winter without use....the following is a method I used to keep the carborator clean which worked great....
approx once a season I would treat the motor with the following mixture....
I would get a 1/2 gal of gasoline and add Techron @ 10 times the recommended dosage..ie.
say recommended Techron dose is 1oz per gal...
1/2x1x10 = 5 oz of Techron
run motor @ idle for approx 1 1/2 hrs......after about 30mins the motor would start to idle rough as the gum began to soften up so I would increase the idle a little to keep motor running....this treatment usually corrected any rough idle that was present..
a couple of times I needed to let the motor sit overnite and repeat the process the next day to get the idle smooth...
the treatment always worked and kept the motor running like a top...
any leftover mixture I dumped in the automobile...
My initial plan was to use approx 10 times the recommended dosage and if that did not work to keep increasing the concentration until the motor did not run on the mixture....thankfully, it worked....I would go to any lengths to avoid tearing down the carborator and soaking it overnite.....
I usually run the motor dry after each use and add a stabilizer and Techron(2 times the recommened dosage) to the gas tank for normal use....

 

[Redfred1]

I have to agree with Scott.Over the years I have tried a bunch of stuff; from kerosine to ATF; tuner cleaner; WD40; carbon tech; the list goes on. Sometimes it worked; most of the time it didn't .I remember my first experience with OB's. Went to buy 3 kits for a Chrysler 85HP.($28 each). Was a envelope consisting of 1 spring; 2 ball bearings; and a needle screw. No gaskets.

Good Luck

 

[Sea Rider]

If you run carb dry after each use, don't need to add any additive to the fuel to clean or maintain clean inside of carb, it's throwing money into the deep blue..

Happy Boating