Newish Tohatsu outboard fuel fitting

[chris95040]

Hi folks,

I have a pretty new tohatsu 6HP outboard with an impossibly small built-in tank and a fitting for an external tank.

The fitting doesn't appear to be what the marine shops suggest is a "tohatsu" fitting. Mine looks more like the yamaha fitting, with a separate stud to snap it in place. (See attached photo for what the tank-side fitting would look like).

I measured the piece on the engine, the fuel barrel is 3/8" diameter, the stud for snapping the fitting in place is 1/4" diameter, and they are about a half inch apart center-to-center. I went to the store and bought a fitting that appeared to have the same measurements, but it's a real bear to get it to snap on, and after about 5 uses the o-ring in the fuel fitting failed. It makes me think I'm using the wrong fitting. Any insights??

[GILow]

I bought one of these recently and it was a bit of non-genuine garbage. Couldn't get it onto the tank fitting without insane amounts of force so took it back and they grudgingly conceded it was crap. Bought a decent quality one from a better chandler and all is good now. Like you, my first thought was that I must have had the wrong fitting, but then the big factory painted label on the tank saying "Yamaha" reassured me.

Sounds to me like you got the same bit-oh-crap I bought?

Matt


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[GILow]

BTW, I read an interesting boat blog recently where the blogger complained of water getting into the built in tank of his otherwise good new Tohatsu outboard. Something to do with the seal on the cap. Might be worth seeing if his issue was an isolated case or something to be aware of.

Our Tohatsu 3.5 must be 30 years old at a guess, still going strong.

Matt


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[chris95040]

Well, my shop has a 'Mercury' fitting like this and a 'Yamaha' fitting, and as far as I could tell the only difference was superficial with the spring loaded locking gizmo, but the merc fits effortlessly whereas the Yamaha puts up a fight.

[GILow]

Interesting... I wish I had kept the packaging, but next time I am at the chandlers I will check whether there was a difference on brands listed on the back of the packet. Neither were genuine parts.

[sailm8]

That is the wrong fitting. I went through this myself and ended up ordering the correct part from Tohatsu. The correct part is more square and cost about 20.00. I went through 2 fittings like the one pictured before figuring out I had the wrong one.
Link:
https://www.tohatsuoutboardparts.com...0221046-3).pdf

[Moontide]

There seem to be a slght difference in the diameter of the fuel "pipe" on the fittings.Thougt I got the right one once and it turned out to be just slightly larger so that the o-ring would not seal. Was OK most of the time, but if I squeezed the bulb gas leaked. Later it started sucking air into the engine. That was no problem at slow speed, but was at higher RPM as the air started getting through to the cylinders

Difference is really minimal but enough to make a difference. I finally had to get an OEM part to make sure it would work.

[chris95040]

Thanks folks, great info.

The mercury fitting doesn't seem to leak - even when I squeeze hard on the primer bulb on the supply hose.

This may be lucky and temporary though - I'll order the OEM part.

[Onthehard]

Tohatsu makes small outboards for several other brands. Mercury is one of these, as well as my Nissan 6hp. The last time I checked Yamaha and Honda were not among the brands using Tohatsu. This may be why Mercury part fits.

[chris95040]

Just to follow up - the mercury part failed this weekend.

So frustrating that there are all these subtly different fittings all achieving the same thing.

[MarkSF]

It would be frustrating if the Tohatsu fitting didn't fit the Tohatsu outboard. The fact that other manufacturer's fittings don't fit is simply unsurprising.

[chris95040]

The parts do "fit", they just don't fit quite right, in some way that is impossible for the user to see (except when it fails prematurely because the sizes APPARENTLY don't quite match up.)

And there is absolutely no good reason for these nearly-identical components to be different from one motor to the next. Thats frustrating.