Tohatsu 6 Sailpro Bogs and Quits Under Load

[RJD]

Went out for a sail today and while motoring out, my three year old Tohatsu 6 Sailpro abruptly quit running. It restarted but would bog under load and died several times as we limped back into the marina. Water cooling discharge was fine with no overheating.

Hadn't run the engine in about three weeks before then, and the gas in the tank is about two months old, so perhaps there was moisture or other contaminants in there - I do add Sea Foam after every fill.

Back at the slip, I checked to make sure the spark plug wasn't fouled, was properly gapped, and was secure. The fuel filter, which I changed at the beginning of the season, looked clear, and the fuel lines showed no sign of leaking. Shook the gas tank to mix the gas a little and then while at the dock with lines secure, ran the engine again - started right up and idled fine for several minutes. Put into gear and powered up and it again bogged down, lost power, and quit. Seems like fuel starvation to me. After quitting, it will start again after two or three pulls.

So, my plan now is to drain the fuel tank, check the fuel tank pick up line for clogging, and try new gas. After that, I'm thinking the air filter, fuel lines, and carburetor is next in line for troubleshooting.

Just thought I'd throw this out there to see if anyone else had this issue with their Tohatsu 6 Sailpro and if so, what they found.

Thanks in advance for any help.

 

[KD3PC]

idles....then bogs when powered up...is likely fuel delivery...jets or that part of the power/acceleration pump circuit. Idle circuit seems to work fine, that pretty much eliminates the filters, lines and such???

I would try a rebuild kit, before you do much more.

 

[RJD]

Update: And all this occurred with the fuel tank vent open. In other words, - no vacuum lock - the primer bulb wasn't collapsing as the motor ran. Also, I just checked the fuel tank pick up line and it was clean.

 

[RJD]

idles....then bogs when powered up...is likely fuel delivery...jets or that part of the power/acceleration pump circuit. Idle circuit seems to work fine, that pretty much eliminates the filters, lines and such???

Makes sense. Thanks.

 

[Tedd]

My Tohatsu 8.8 has a vacuum-driven fuel pump on the side of the carburetor. I'm guessing yours has something similar. I would check that for either a torn membrane or blocked vacuum line.

 

[JimInPB]

Sounds to me like you might have water in the float bowl. Fuel floats on top of water & a little bit floating on top may be enough to run the idle jet. When you open up the throttle, you might then start to move enough liquid that you start to suck up the water. Try draining the float bowl, then restarting.

You didn't say if your fuel filter is a water blocking type or not.

Could also be an ignition problem. When things happen suddenly to an engine that was running fine a few minutes before, the issue is often electrical.

 

[Gene Neill]

Do you run ethanol free gas?

 

[Johann]

Sounds like you need to clean the carb. I’ve had the same issue with a tohatsu 6hp, but it’s an easy fix. To prevent this from happening in the future, use E0 fuel, disconnect the fuel line and run til it quits if your not gonna run it for a few days, and drain the carb if it’s gonna be more than a few weeks...

 

[Jacktar]

Never had this problem, will run with fuel line unplugged for 10 minutes or so when I run it dry after docking. I use ethanol free gas. Sounds like your carb is not getting gas via the pump if it was it would run for quite a while on what is in the float chamber. Most likely bad pump or moving blockage in line to plug in motor.

 

[RJD]

I don't run ethanol free fuel. I'll do a further inspection of the fuel system but I'm betting the carb is gummed up from running fuel with ethanol. Thanks for the help everyone.

 

[LakeShark]

Ethanol in the fuel just makes a mess of everything. I used to work for a Johnsen Evinrude shop for a time and we used to spray this stuff through all motors that came in before we went any further in troubleshooting.

https://www.wholesalemarine.com/joh...MI_K2wtqf11gIVCwppCh1wbg3oEAYYASABEgKDm_D_BwE

It will remove carbon and fuel gum from the cylinder head and the carburetor. But it is about as nasty as it gets so if you're at all environmentally conscious then I would not recommend it. We would run the motor in a test tank and the whole test area will be enveloped in smoke as the motor coughs, spits, and puts out the nastiest stuff you have ever seen into the water (fuel, carbon, gum, tar like balls etc..). Afterward the motor would run better and we would preform regular maintenance (at amin you will need to clean the plugs to get it to run properly again). Its not a miracle in a can but it can help eliminate many minor issues with fuel deposits in the motor. I still use it every fall before I winterise my motor. It takes 1 can per shot regardless of engine size and by all means don't be stingy with the spay (directions on can). I would recommend it before you tear down the whole carb for what is just a low idle issue likely from fuel. It is available from almost any dealer for outboards and Evinrude, Mercury, etc... all have their own version of the can but they do the same thing. Hope it helps.

 

[kloudie1]

Agree, sounds like fuel delivery,, In addition to good info above (clean carb, use E-0, fuel pump look-see) Check that there is not an air leak in the fuel line quick-connects.. bad o-ring or small crack in fitting etc.. a small air leak (in fuel line or in vac line to pump) can generate those exact symptoms.

 

[jwing]

I use ethanol-free fuel. I also let the fuel in the engine burn off at the end of the day (that is, I don't hit the kill switch). And there is still some fuel left in the bowl. I drain that by turning a screw that acts as a drain valve (I had to read the instructions to learn about that). I do all those religiously. Anyhow, after all that, my motor developed the same symptoms, I figured it was time to learn how to clean the fuel jets, but I tried the lazy way first: I ran my motor in neutral a fairly high rpm while burning fuel that was rather rich in gunk cleaning and water removing chemicals. I can't remember which ones I used - whatever I had sitting on the shelf. That worked pretty good, but the charm was turning up the idle speed a touch. I don't know why that helped, but it did. Maybe this winter I'll clean the fuel jets properly (Nah, who am I trying to kid? If it ain't broke, don't fix it).

 

[Gene Neill]

For whatever it's worth, I never run any carb dry, or do anything else, EXCEPT that ethanol will never touch any small engine I own. Ever since I switched to non eth gas I have never had any problems with anything - chainsaw, leaf blower, lawn mower, outboard motor(s), generator, nothing. Everything (including the Tohatsu) starts on the first or second pull, every time, even after weeks or even months of disuse.

I'm not arguing against running dry, or the use of any additives, by any means. Just saying I have had perfect results without doing either.

 

[RussC]

Certainly sounds like a partially plugged main jet. easy enough to determine. run the engine at moderate/high speed. when it starts to faulter, pull the choke out halfway and see if it doesn't run smoother. I suspect it will, which says yes, the main jet is partially plugged. wile you're at it, you might run the motor at high speed and yank the choke all the way on momentarily several times. sometimes this will clear the blockage, and sometimes not, but worth a try before pulling the carb off to clean.

.02

 

[Benny17441]

Sounds like a gummed up carburetor to me. Pull the carb out disassemble and clean. Soak body and parts in a carburetor cleaner fluid and then used compressed air to insure all passages are clear. It is not always possible to properly clean these small carburetors so if the problem persists a replacement unit might be in order.

 

[JimInPB]

If it is a gummed up carb jet, the quick & easy way to do something about it, on a motor that does still run a little bit, is to buy a small can of carb & injector cleaner that you mix with the fuel & run a bit of that through the motor. Gumout seems to be the most common name brand. Some people like Techron (expensive). I have been using the store brand from Auto Zone lately with good results. About 1 oz in a half gallon of gas is usually enough to get the job done on a small engine. I like to use up all the gas with the additive in it & then run a little straight gas through after. I have had small engines get clogged carbs after sitting for long periods of time, even with ethanol free gas.

My most recent episode of this was on a generator that a friend tried to get going after Hurricane Irma came to visit. The generator only ran with the choke on half way & the exhaust system was glowing orange. 10 minutes with the additive & the glow started to fade. 15 minutes after that, we were able to shut the choke off & he was able to run the generator for the remaining 4 days until power came back on.

My first step would still be to drain the float bowl & see what comes out. If you find water, that indicates one problem. If you get almost nothing to come out, that would tend to indicate a different problem. If you get a full bowl of good clean fuel, then I'd check to see if you have a good strong spark. If you do, then I would look into cleaning the carb.

If squeezing a primer bulb makes the motor run fine, then you probably have a bad fuel pump or an air leak in the fuel system.

 

[RussC]

If squeezing a primer bulb makes the motor run fine, then you probably have a bad fuel pump or an air leak in the fuel system.

Yup. Good point.

 

[RJD]

I did an INTERNET search of ethanol-free gas stations in the northern VA/MD area and while several popped up, when I went there they all had 10% ethanol. Looks like ethanol-free might not be an option for me. So, with a fresh tank of gas with Sea Foam added, I tried the little Tohatsu again and got the same bogging - so it wasn't contaminated fuel.

I took the carburetor apart and was surprised NOT to find it all gummed-up after running it with fuel with ethanol for the last three years - perhaps a testament to using Sea Foam as an additive. Anyway, removed the jets and blasted all the components with carburetor cleaner, and made sure the fuel lines and filter were clear of obstruction. Put it back together and viola - worked like a charm - no bogging whatsoever. Whatever spec of dirt was clogging up the system is gone now.

Much obliged for all the good advice. Will be out sailing this weekend.

 

[CaptDon01]

For what it's worth, I've had two Tohatsu 6 HP Sail-Pro's, (first one was stolen after 3 years), bought another identical one, had it now for a couple years, both have never had a drop of ethanol free gas, I always use premium fuel, Sta-Bil, and about 1/3 can of Seafoam into my 6 gallon tank. Never had any fuel issues. A friend had a similar issue that your describing and it turned out to be the fuel hose was breaking down inside, no evidence of a failure, bulb was fine, replaced the hose and problem gone. Very strange. Might try and borrow a friends fuel line, Tohatsu, Nissan, or Mercury will all work, and see if the problem goes away. For the heck of it, pull the oil plug and see if there is any fuel in the engine oil. The fuel pump has a thin diaphragm that could be the issue also.

Don