Tohatsu 6hp still not broke in having carb issues?

[Black Rat]

I bought the 6hp Tohatsu to use on my 14' SIB when island hopping in heavy waves, specifically, when trying to beach it and pull up out of the water to camp out. I haven't used it yet due to the weather has been fantastic so I kept the 25hp on. Anyway this spring when I took the 6hp out in a fishing boat it started fine, idled perfect, but as soon as I throttled up it bogged and died. I can keep it running with the choke but something is amiss. It only has 5 hours on it, still under warranty.

 

[JimS123]

Small Tohatsus are noted for carb problems. They recommend that the carb be run out after each use to keep the small jets clean.

If it has 5 hours, then it must have been run. Before I took it to the dealer I would try running some Gumout or other carb cleaner thru it. That could be an easy fix, and it has worked for me.

 

[Sea Eagle Mark]

Hey BR,
We got a 3yo 6hp Tohatsu also and love it. It is picky about gasoline, especially E10. Only had an issue once. Here's what works for me. FRESH gas is a must! Just a few weeks in the summer sun and it's toast. Unless I'm using up the small internal tank every week or so I drain and refill. Even MORE important if you got a 3 gallon tank sitting in the boat for weeks on end unused take it home dump it in the car and refill with fresh gas. If your using the boat often you shouldn't have a problem. End of season empty tanks and run motor dry. Hope this helps.

 

[JimS123]

Hey BR,
We got a 3yo 6hp Tohatsu also and love it. It is picky about gasoline, especially E10. Only had an issue once. Here's what works for me. FRESH gas is a must! Just a few weeks in the summer sun and it's toast. Unless I'm using up the small internal tank every week or so I drain and refill. Even MORE important if you got a 3 gallon tank sitting in the boat for weeks on end unused take it home dump it in the car and refill with fresh gas. If your using the boat often you shouldn't have a problem. End of season empty tanks and run motor dry. Hope this helps.

I have a little Tohatsu kicker on 2 of my boats. One is 3 years old and the other is 2. Both run on 3 gal tanks. I only use them once a month or so just to keep them broken in. I ONLY use E10 and fill the tank up only once per year. adding Stabil each time.. So far I have been lucky and didn't need to use them for a safety, so the gas is a year old when I put it in the lawnmower and refill.

I have never had a problem with either one, but after buying the first one and reading about the carb issues, as a matter of routine I disconnect the fuel line and run out as much gas as I can after each use. As a matter of fact, Mercury Marine recommends that very procedure, and they also have no issues with using E10.

 

[Sea Rider]

Indpenedently if running 2 or 4 stroke motors once in a while or constantly, take advantege to run carb dry while being flushed on muffs, barrel or thru the flushing port, the carb's bowl fuel contents should give 5 minutes of flushing.

Happy Boating​

 

[Black Rat]

Thanks for the replies. After reviewing them I decided to get a second carb and take the original, clean it, and install a high altitude kit for a Lake Powell trip on my bucket list next year. The new carb was a perfect fit but does has a slight hesitation when I open it up, but is fine if do a slow rev up. I did change out the spark plug which appeared dry but had an slight green tinge to it. Hope to take the OB out tomorrow for final test.

 

[racerone]

Run the carburetor dry when done boating.----A dry carburetor does not gum up.

 

[Sea Rider]

So, plan boating at 2 different altitudes, say sea level ? and a at Lake Powell right ? Nice to swap the carb for both altitude scenarios, but at the higher one will need to go for less prop pitch for the combo to run better than at a less height altitude.

At your current boating location, what's the max wot rpm achieved as usually loaded on flat calm water cond ? to know that will need to install an induction tach, what's the current installed 3 blade diam/pitch prop ?

Happy Boating​

 

[Black Rat]

So, plan boating at 2 different altitudes, say sea level ? and a at Lake Powell right ? Nice to swap the carb for both altitude scenarios, but at the higher one will need to go for less prop pitch for the combo to run better than at a less height altitude.

At your current boating location, what's the max wot rpm achieved as usually loaded on flat calm water cond ? to know that will need to install an induction tach, what's the current installed 3 blade diam/pitch prop ?

Happy Boating​

 

[Black Rat]

Yes I'm at sea level and plan Lake Powell next year being around 3560 feet above sea level. Factory prop is 7.8 x 8 three blade. I don't have a tach but I see they are reasonable in price and easy to use. Looks like I'll have to get the tach first and then probably drop down one step in prop pitch to 7.7 x 7 and see what my max RPM is with tack. My understanding is 5-6K is max?

 

[Sea Rider]

Yes I'm at sea level and plan Lake Powell next year being around 3560 feet above sea level. Factory prop is 7.8 x 8 three blade. I don't have a tach but I see they are reasonable in price and easy to use. Looks like I'll have to get the tach first and then probably drop down one step in prop pitch to 7.7 x 7 and see what my max RPM is with tack. My understanding is 5-6K is max?

Would recommend order a Hardline hour/tach meter code : HR-8061-2 check Amazon, cost a tad more than other brands but way to go guaranteed. To get the full picture, aside the 25 HP that powers that 14 footer Sib, plan using the 6 HP motor also. Will both 6 & 25 HP motors be used at Lake Powell or just the 6 ?

The 6 HP wot rpm range factory stated is : 5000-6000 rpm. Right now don't know at which sea level boating is the motor revving at full throttle. Once the tach is installed go for a wot run on flat calm water cond and report max achieved wot rpm as loaded, don't overload that large sib with too many souls on board, max 2 would be reasonable for the combo to plane much better and faster at sea level and at Lake Powell. Btw, 1,078 meters of altitude it's a nice walk around the park. At 2,500-3,000 meters of elevation the walk around the park tires more...

Happy Boating​

 

[km1125]

Yes I'm at sea level and plan Lake Powell next year being around 3560 feet above sea level. Factory prop is 7.8 x 8 three blade. I don't have a tach but I see they are reasonable in price and easy to use. Looks like I'll have to get the tach first and then probably drop down one step in prop pitch to 7.7 x 7 and see what my max RPM is with tack. My understanding is 5-6K is max?

Unless you're really interested in top speed, I'd suggest getting a "high thrust" prop to replace your current one. It's a 6 pitch but more importantly it's got much larger blades so it can push a lot of water. It would help you get on plane much easier, especially if you're got a little more load than normal. If you're running very lightly loaded on flat water you might have to watch so you don't go over max RPM (but don't all the new ones have an RPM limiter anyways?), but in any kind of surf or heavier loaded you'll like the fact that the engine can push much more and give you more control.

 

[Sea Rider]

A high thrust prop it's intended to move high loads such as sailboats, not for light Sibs as a 14 footer, the OP has not mentioned how many souls will be onboard. A 3 blade 7.8- 7-6 pitched will do the trick depending which was the reported wot rpm achieved as loaded with current 8 pitch.

Happy Boating​

 

[km1125]

All I can say is that I had a 6HP motor with an 8 pitch prop on an 8'6" SIB and it would only get on plane with just me in the boat. I dropped down to that high-thrust prop with the 6" pitch and it no longer had a problem getting two of us with a dog and a full cooler up on plane. I moved it over to a 10.5 RIB and had the same results.

 

[Sea Rider]

A 14 footer Sib well inflated achieves less hull drag and will plane faster due to being much larger than a 8.6 Sib which achieves more hull drag due to its shorter size. A Rib of equal size to a Sib planes much faster. Let's wait till the OP report his wot rpm run as loaded with an 8 pitch and go from there if that's OK with you ?

Tried a 380 Sib powered with a Tohatsu 5 HP motor, with factory delivered 3 blade 8.9 x 8 prop was hard to plane, installed a standard 3 blade 8.9 x 6 prop and the motor gained 1000 + wot revs and now revs to its max wot rpm range and planes as a breeze, once there can reduce the throttle to ¾ and keep the Sib on plane while screaming much less...

Happy Boating​

 

[Black Rat]

Got the tach as recommended but no time for test until end of month. I'm seeing what they call an "elephant ear" 8.3 X 6.0 prop...the 7.9 X 6.0 not to be found yet. Be great to have prop and the tach for the test. Got a 10 day trip planned in August in Lake Superior island hopping and if the waves are big the 25 HP OB is too much power I can only idle through it. The 6hp with the "elephant ear" prop would work fine plus we could bring the boat up on beach without a heavy 175 pound motor on rear end.

 

[Black Rat]

Got the tach as recommended but no time for test until end of month. I'm seeing what they call an "elephant ear" 8.3 X 6.0 prop...the 7.9 X 6.0 not to be found yet. Be great to have prop and the tach for the test. Got a 10 day trip planned in August in Lake Superior island hopping and if the waves are big the 25 HP OB is too much power I can only idle through it. The 6hp with the "elephant ear" prop would work fine plus we could bring the boat up on beach without a heavy 175 pound motor on rear end.

Sweet...the prop is on the way too so will have both for test in a week.

 

[Black Rat]

Prop was delayed a week. Doubtful I can test until June 12th now. I did get the tach reading on the standard prop shipped with engine 7.8 x 8 and max WOT 5490 RPM was what I saw. I noticed I had to get on plane with the 13 foot fishing boat to get max RPM too. The new carb ran great for two solid hours at all speeds. I have yet to tear the original down to see how gunked up it was.

 

[Sea Rider]

Congrats, now you know that in order to play properly with prop pitches need to install an induction tach, with current 7.8 x 8 prop the motor if revving at 5490 is revving towards it's middle side of its wot rpm range which is 5000-6000 rpm. How loaded was the Sib when the tach dialed 5490 revs ?

A 6 pitch will bump current wot revs towards its max and probably over. Test both standard and high thrust props and check their individual wot test run and report. The high trust prop should achieve less wot rpm compared to the standard six ?

To get the max fun out of that combo, inflate all air chambers to min 3.0 PSI keel included, a rigid Sib will glide much better on water....

Happy Boating​

 

[Black Rat]

Got a two hour test in today finally with the elephant ear prop and max rpm I saw was 5970 rpm. Most of the time it ran at 5850. Ran great and definitely at around 3500 rpm seem to be a nice spot for pushing.