New 9.8 Nissan Poor idle & dirty plugs @10Hrs

[Hunter22]

I just got a new 9.8 Nissan and after 10 hours it was running rough at times and poor idle. The first few hours it purred like a kitten. I pulled the plugs and they were unusally dirty for just 10 hours-black carbon like buildup already. I cleaned them but it still won't idle smooth. Seems to run ok with trottle up. Could this be the fuel? I used 87 Octane as per the manual. Should I run a higher Octane or is this another problem?

 

[TOHATSU GURU]

Re: New 9.8 Nissan Poor idle & dirty plugs @10Hrs

Clean the carb and start running the gas out of the engine each time you come back to the dock...It probably wouldn't hurt to let your local dealer check the engine over to make sure everything is the way God and the Japanese intended it to be.

 

[clough]

Re: New 9.8 Nissan Poor idle & dirty plugs @10Hrs

I've had a similar problem, and, it seems to take too long a time to warm up. When its warm however, its smooth as silk. I have started to run the gas out of the engine each time and it seemed to help. What would you say to a little seafoam or something in the next tank of gas to flush the jets??? Thanks (sorry to invade your post Forrester).

 

[TOHATSU GURU]

Re: New 9.8 Nissan Poor idle & dirty plugs @10Hrs

Fuel additives usually do not hurt and often help....But, if you run the engine at an idle when you are done for the day you should eliminate 99.99% of the problem. As to the engine taking a long time to warm up....Other than running 30 weight oil and a higher idle, there isn't much that you can do. The number one problem for all brands and models of 4-strokes is that they all run cold due to their raw water cooling systems. Keep in mind that 4-stroke engines only did three things better than 2-strokes when the EPA got involved and screwed things up. Better emmisions, quieter, and better fuel economy at slow speeds. Today, well they are still a little more quiet than DFI outboards, but that is their only advantage.