Tohatsu 2-stroke dies shortly after running at WOT, hard to restart

[01kiwijohn]

I have a little Yamaha that sometimes does similar. I found that I could get back home by giving it about half choke. Turns out, there was a minute piece of dirt in the main jet, which must've floated around and got sucked into the jet. At first I didn't see it but, after cleaning the carb out, with my compressor, pice by piece, it runs just fine.

[a64pilot]

Originally Posted by DefinitelyMe

When ours did this it was due to a bit of dirt in the carb.

I wasn’t very clear, but that would be my suggestion, my Jet Ski had been modified with an expansion chamber, but the carburetor not re-jetted, I had jet drills so I just drilled it out until it’s plug chops looked good.

But lean means hot and hot of course can seize an engine, and a lot of little two stroke are amazingly tolerant of seizure.

[sailingchiro]

If fuel was left in the carb, maybe you have a float sticking. I would change the fuel line with bulb and fuel filter. Then take carb out for a good cleaning and make sure the float isn't sticking open or closed.

Had a problem with my float with the angle of the boat on trying to get on plane. The motor float wasn't set up for a big change of angle of attack

[mayberrybfd]

Its the Ethanol. Won’t run on mine either

[Bundyon]

Some small outboards have a gauze strainer at the fuel tap, at wot any crap in & around that gauze gets sucked against it restricting fuel flow. Also, whenever you are shutting down your outboard for the day, you should practice disconnecting the fuel line & let it run out of fuel, preferably just above idle. This stops oil residue & gum forming in the jets. Also worth getting yourself a cheap (ebay) sonic bath. Dismantle the carby and put all the brass bits (jet's etc) into the sonic bath, if you don't have the correct sonic liquid, use hot water and dishwashing liquid. This cleans the gum & built up residue from the inside of the jets and seats. Reassemble & refit carby, throw a new plug at it & providing the engine is good mechanically, she'll run like it's supposed to.

[Jetx]

Thanks everyone for the suggestions. Today replaced everything between the tank and the outboard... all hose, new demand valve and bulb. When removing old hose in sections (tank is in the bow, with hose running underneath the inner floor), it was delaminated in the few places that I cut, with amber grease/gunk between the layers.

Haven't had a chance to run it much today, but actually seems to be idling and running more smoothly at low speeds. Will exercise it some more and run at WOT for a few spells over the next few days. Crossing fingers and hoping the hose replacement was all that was needed.

[Library70]

Jetx, try running it again at WOT, when it stalls pull the spark plugs. If they are dry it’s starving for fuel if they are damp it’s most likely a spark issue, if they are wet it’s flooding. Spark plugs are a simple and effective diagnostic tool. My 9.8 Tohatsu started stalling at high speed and was very difficult to restart. Pulled the plugs and they were wet, turned out to be a leaking carburetor bowl gasket. On the 9.8 a leaking bowl gasket can allow fuel to flow from the fuel pump into the carburetor bypassing the needle valve, the problem is exasperated at higher rpms. I believe the 18hp a similar carburetor setup.

[GeneM]

I didn't see anyone say to rebuild the carburetor. I didn't clean mine for three years and it began to not get to high rpm. After taking apart and thorough cleaning with carb cleaner, it worked well.

[Compass790]

Originally Posted by GeneM

I didn't see anyone say to rebuild the carburetor. I didn't clean mine for three years and it began to not get to high rpm. After taking apart and thorough cleaning with carb cleaner, it worked well.

I believe I did suggest cleaning carb in post #10

[AlanR]

[QUOTE=DeltaBoy;3135755]

Originally Posted by anacapaisland42

What is WOT?
Bill





Wide open throttle

TFTI

You'll have to work it out, like we had to with WOT.

[capt.rob]

i had similar issues in the past with that grey colored fuel hose with an interior liner it drove me nuts till I figured it out. Replace that hose it will collaps on the interior and show no signs on the outside. It's junk get regular fuel hose not the grey or any color hose with interior liner.They will work when they are under pressure from a fuel pump that holds the liner open but with an outboard the pump is on the motor making them a suction line and the liner will collaps.

[Bill O]

Originally Posted by Jetx

Thanks everyone for the suggestions. Today replaced everything between the tank and the outboard... all hose, new demand valve and bulb. When removing old hose in sections (tank is in the bow, with hose running underneath the inner floor), it was delaminated in the few places that I cut, with amber grease/gunk between the layers.

Haven't had a chance to run it much today, but actually seems to be idling and running more smoothly at low speeds. Will exercise it some more and run at WOT for a few spells over the next few days. Crossing fingers and hoping the hose replacement was all that was needed.

Good first choice. Have seen those "cheap" plastic hoses delaminate and it looks like plastic wrap clogging the whole tube. At first you get random shutdowns, then it will get worse and really restrict fuel flow.

Originally Posted by capt.rob

It's junk get regular fuel hose not the grey or any color hose with interior liner.They will work when they are under pressure from a fuel pump that holds the liner open but with an outboard the pump is on the motor making them a suction line and the liner will collaps.

Agree w/Rob and hopefully you got regular rubber fuel hose for your run. Thinking this will fix your problem.
Let us know.

[Bill O]

Here is an example of what the grey plastic fuel hose looks like when the inner liner collapses.

[kmacdonald]

Tip 1) Buy a cheap $40 ultrasonic cleaner and clean the carb in it with gasoline. Fill the ultrasonic cleaner with water and put the carb (with bowl removed) in a plastic bottle with the top cut off. Add gas to plastic bottle to cover the carb. Put in ultrasonic cleaner for 10 minutes.
Tip 2) Use a new gasket when mounting the carb. The seal between the carb and intake manifold is critical. You want the air drawn thru the carb, not thru the joint between the carb and engine. This is usually the problem when people say they cleaned the carb and it didn't fix the problem.

[hzcruiser]

Originally Posted by GeneM

[....] it began to not get to high rpm. After taking apart and thorough cleaning with carb cleaner, it worked well.

The OP had different symptoms to yours.