Tohatsu 9.8 2 Stroke Outboard Misfire

[Zneg4]

Hi all.
Wondering if anyone has had a similar experience to mine.
I used my Tohatsu 9.8 2 stroke recently and after running fine for 15 minutes at 3/4 throttle, the revs started to drop, and I noticed it had begun to overheat. I let it tick over to cool down, then stopped the engine. Upon lifting the leg, I found the wash plug had fallen out.
I guess this meant the cooling water was partially by-passing the cooling system.
I managed to limp home on tick over with cooling water coming out of telltale.
When I flushed the engine (as I always do after use in saltwater) I found the engine starts easily but when revved, it ' hunts' ie it revs, dies then revs etc.
I have fitted new plugs.
Also checked fuel line for air leaks but no different.
It sounds like fuel starvation, but I am worried that the short overheat has affected the crankcase compression. Before I start stripping carbs and further, has anyone any advice?
Many thanks

 

[fredrussell]

You could put a compression tester on it. The type that screws into the spark plug hole. Not expensive, and easy to use.

 

[Zneg4]

You could put a compression tester on it. The type that screws into the spark plug hole. Not expensive, and easy to use.

Thanks. I will try that, but I fear the problem may be crankcase compression. A normal compression test will not show that.

 

[CliveF]

If you can see round the crank case just smother it with a strong soapy water solution and run it , see if it starts blowing bubbles. each cycle should be 50 % blow 50% suck so you should see a tell take if it is leaking.

It could also be that the hunting is totally coincidental to the wash plug falling out and is in fact due to old / contaminated fuel and or stirred up crap in the system .

If you do not see bubbles I would fully purge and clean the fuel system / carb before getting into any thing more serious.

Regards Clive

 

[Zneg4]

If you can see round the crank case just smother it with a strong soapy water solution and run it , see if it starts blowing bubbles. each cycle should be 50 % blow 50% suck so you should see a tell take if it is leading.

It could also be that the hunting is totally coincidental to the wash plug falling out and is in fact due to old / contaminated fuel and or stirred up crap in the system .

If you do not see bubbles I would fully purge and clean the fuel system / carb before getting into any thing more serious.

Regards Clive

Thanks Clive. That's great advice.