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cthoops 07-08-2013 07:17 AM

Tohatsu troubles
We have a 2010 Tohatsu 9.8 hp outboard on our boat. The previous owner said it could be temperamental.

It ran pretty well for the first six weeks or so, but now it either runs very smoothly, or it's very rough and acts like it wants to stall (and occasionally does). When it's running rough, increasing/decreasing the throttle or fiddling with the choke doesn't help it. Yesterday we went to the dock to get water, etc. and it purred right along. On the way back, it stuttered away (made for a stressful return to the mooring).

Before the season we put in a new water/fuel separator filter, we always run it dry, and we use high octane fuel and put stabilizer in it. We top off the tank frequently (it's an external 3+ gallon tank), and it gets used once a week.

At this point we're not comfortable heading out for a sail until we get it straightened out. Any thoughts? Would it be something that we can try to fix ourselves? Mr. Cthoops was an airframes mechanic 30 years ago in the Marines and he can fix any bicycle, but he doesn't consider himself a motor head. I'm really good at cheering him on and handing him things.

Any suggestions would be greatly appreciated. Thanks.

Shinook 07-08-2013 07:27 AM

Re: Tohatsu troubles
It's a 2010 model? I think they come with 3 yr warranties, but I could be mistaken. You might get the serial # and give Tohatsu a call, see if it's still covered.

That's about all I can do with a 4-stroke, remove it and take it to someone else to deal with :P

cthoops 07-08-2013 07:35 AM

Re: Tohatsu troubles
If it's at all related to the ethanol (which I suspect it is, based on my online research), it won't be covered under the warranty. I won't get into how I think it's bogus that they can exempt from the warranty any issues related to ethanol gas, given that we have no option but to purchase that around here.

Sal Paradise 07-08-2013 07:49 AM

Re: Tohatsu troubles
The electronics are so good on these now that it really has to be the fuel system. Makes it simple. Either the carb needs to be cleaned (which is very easy) or the fuel lines and/or connectors need to be replaced.

tsell 07-08-2013 07:54 AM

Re: Tohatsu troubles
We have a 2009 Tohatsu 9.8, with what sounds like the same issues. I had the carb rebuilt about 2 weeks ago, and it ran great until last Sunday. I ran it dry and started it again on Friday, and we are back to square one.

I had been leaving the fuel bowl full since it sat no more than a couple of days at a time, but Sunday I decided to run it dry. My very amateur thought is that when it is really warm (it has been in the 90's) that running it dry caused the problem, since the fuel evaporates much more quickly in the heat, leaving behind the varnishes and residue that wrecks fuel systems.

T37Chef 07-08-2013 07:54 AM

Its probably the carburetor which is easily disassembled and clean using a Carb cleaner. You will be surprised just how easy it is.

I have the same engine, it was stored for a couple years and had problems running smooth. I took apart the Carb and cleaned it and of will start on the first pull and runs smooth as ever.

The fuel is the problem, not the engine

rhr1956 07-08-2013 09:01 AM

Re: Tohatsu troubles
Since it runs smooth sometimes and runs rough at others, I'm guessing it's the fuel. I think I would dump the gas, get some fresh at a different gas pump.
Change the spark plug/plugs and give it a go. Run the piss out of it...hard. If that doesn't make things better, take it to the shop.

dabnis 07-08-2013 10:25 AM

Re: Tohatsu troubles
"Running it dry" will leave a small amount of fuel in the bowl. Suggest you drain it instead. Just had the same problem with my generator which I haven't run for a long time.
I drain the carb after each use. Anyway, I dropped the bowl, which was perfectly clean, turned the gas on and manually "tickeled" the float up and down many times. It worked, ran perfectly without having to remove the carb.

Removing the carb and cleaning the jets and air passages is not difficult. Suggest you work over a large towel and place the parts top side up in the sequence, cleaning with a thin wire, compressed air and/or spray carb cleaner. No hands on experience with your particular carb but have done many others. Be aware of little check balls and/or springs, work slowly and carefully. Worst case is if your fix doesn't work you can take it, the carb, to a shop. Agree with the earlier post that modern ignitions are basically bullet proof.

Paul T

cthoops 07-08-2013 11:42 AM

Re: Tohatsu troubles
These are all great suggestions with your theories confirming ours - that it's likely the carb. We've never removed one before so it should be entertaining, but I'm taking to heart the fact that it doesn't seem to be a difficult job.

Would it be better to use the spray cleaner or should we let it soak in the other stuff?

TQA 07-08-2013 02:35 PM

Re: Tohatsu troubles
2 st or 4 st ?

If 2 st try new plugs.

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