Tohatsu 8 HP 2 stroke issue

[Markdrywa]

I have a 2002 M8B engine that runs rough about 1/4-full throttle. If I speed up or slow down a little it will smooth out. At idle it sounds great. I also noticed that I am not getting the power out of the engine like I did a few years ago.

When I first start it seems to smoke more that it did last year and I have noticed a small amount of fuel\oil in the water. We have replaced the diaphragms in the fuel pump and started with a fresh tank of gas with the correct oil mixture. I checked the compression and both cylinders were at 64. Not sure what the correct compression should be.

Any help would be appreciated

 

[Sea Rider]

Re: Tohatsu 8 HP 2 stroke issue

Service manual states 57 PSI, try power tuner to clean piston rings, pistons and cylinder walls and a good carb clean as well. Are plugs correctly gapped ? Engines when cold are natural smokers.

Happy Boating

 

[Markdrywa]

Re: Tohatsu 8 HP 2 stroke issue

Thanks for the quick response.

I forgot to mention that the plugs were also replaced and gapped correctly. I wil try the power tuner and give the carb a good cleaning.

 

[Sea Rider]

Re: Tohatsu 8 HP 2 stroke issue

You are welcome, forgot to mention that compression test must be made with hot engine, throttle completely opened at wot, pull cord minimum 3-4 pulls to have a good lecture. Let engine warm at neutral, fast idle and squirt power tuner through carb untill engine dies, let rest for 30 minutes, pull cord with engine off to move pistons to different position, let stand 30 more minutes. Turn engine on and go for a spin at 3/4 throttle, then wot for 1 minute. Should feel the engine differently than before if it was a carbon build-up.

If not using carbon guard on gasoline, you should apply power tuner each 100 hours to maintain engine in excellent working conditions. If squirting PTwith carb silencer is an issue, remove silencer and place nozzle inside carb throat. Let us know if bettered the lost power.

Update: After full servicing a 15 HP engine noted that didn't respond nicely to full throttle, had much of the symptons you describe, so seems purge time. Removed small lower filter from elbow tubing inserted inverted on a hot water faucett, open water and with fingernail pressed the small ball inside connector to clean complete gas passages, reinstall, then connected the hose to tank and engine, removed filter holder & filter, placed a pan under holder and primed bulb vertically and horizontal and purged a complete 1 litter out. To my surprise very small near transparent debris was found on pan. Placed back filter and went for a spin, now the engine runs as a champ, has regained it's wot lost power. This cleaning method really works and should be performed after finishing a full maintenance to any engine.

Happy Boating