Tohatsu 3.5 gas dump

[zachduckworth]

Hi all,
So I was out in my dinghy at a mooring field this weekend. My boat came with a Tohatsu 3.5 that has always had issues shifting. If I try to slowly rev it up the engine does, but it revs with jerky turns on the throttle.
I assumed that I needed to clean the carburetor but hadn’t gotten around to it.

So then, yesterday I was out in the dinghy and the motor was really giving me issues. It died and I had to start it probably a half dozen times. Then, I smelled gas and noticed that gas was pouring out of two little hoses on the back of the motor, behind the cooling water exit hose.

Long story short, the entire gas tank drained out through the hoses and my buddy and I ended up having to row back to the boat.

The Tonhatsu manual I found online doesn’t have the three hoses, only the single coolant hose. Has anyone else had this issue/ had this happen/ know what it may have been? I’ve got the engine here at my apartment now, will be taking it apart shortly to begin troubleshooting and fixing, plus cleaning carburetor…

[Celestialsailor]

Possibly stuck float or needle.

[Networker]

Toss it in the ocean and get a new one

[zachduckworth]

Ok - I took it apart, the hose the gas came out of goes to the carburetor. I’m still researching. Any advice as to the right direction is of course appreciated.

[kipwrite]

Celestial sailor gave you the answer. This is likely caused by a stuck carburetor float or needle. Or a broken fuel line.

[Bill O]

Is it a 2 or 4 stroke? Also possibly a year?

2 strokes were very reliable, but do need the main jets cleaned every once in a while.

May need to replace the hose from the tank to the carb or use better clamps to secure it.
Another thing that may get clogged in those motors is the internal tank filter. Also check to see if there is any water build up inside the tank.

[Shrew]

Originally Posted by zachduckworth

Ok - I took it apart, the hose the gas came out of goes to the carburetor. I’m still researching. Any advice as to the right direction is of course appreciated.

Your float is stuck. When the float drops, a needle attacked to the float drops with it, opening the aperture that allow fuel to flow from the tank into the fuel bowl on the carb. As the fuel in the bowl rises, so does the float and the needle slowing closes the fuel aperture again.

The fuel bowl on the carb has an overflow tube.

When the float sticks down, the aperture stays open and the fuel bowl fills faster than the jet siphoning fuel from the bowl into the venturi can keep up. The excess fuel is dumped out the overflow tube.

1) varnish build-up from ethenol or long storage periods can cause this.

2) corrosion from the water gathered by ethenol (ehtenol is hygroscopic) can cause this.

The best solution is IMHO is to simply replace the carb.

With the new carb.

1) Always use starton/seafoam along with a stabilizer for ethenol gas

2) Run the carb dry if the motor is not going to be run for a few days.

[PNWSalmon]

The shifting issue is solvable too, just a few adjustments. These are great engines if you service them every couple of years.

[Madehn]

Stuck float or stuck needle that the float pushes on. Clean it out once. Easy job. If it happens again replace the whole carb. I carry an extra carb for this same scenario.

[zachduckworth]

Thanks for the advice. I was able to take the diagnosis here to youtube and figured out what I need to do (clean carb, fix float or needle). I think I’ll take the advice of having one on hand just in case it goes sideways on me during a trip.