fouling plugs

[Eric Herbert]

Was wondering if anyone is having problems fouling spark plugs in a 200 optimax. I have had the boat out twice this year, the 1st time all the plugs fouled out at idle, I swaped them out (and had someone tell me low battery voltage and slow cranking can cause this) so I also updated by battery to a 1000 mca battery!! went back to the lake and fouled them out again, the motor is a 2007 with only 99 hours on it, what can be going on,

 

[Ralph Hayden]

From my manual (150 Opti)



OPERATION



Setting Trim Angle While Running Engine at Idle Speed



The exhaust relief hole on the outboard may become submerged if the outboard is trimmed full in while running at idle speed. This will cause exhaust restriction, rough idle, excessive smoke, and fouled spark plugs. If this condition exists, trim the outboard up until the exhaust relief hole is out of the water. The outboard should be lowered for accelerating from a standing start or from idle speed.



Not sure if this is what's causing your problem.

 

[Derick Leppin]

Mine did the same thing when I bought if used. I took it to the local dealer where there decarborized it and it still fouled plugs. It ended up being bad gas. I ran out the old gas and no more problems since. Oh make sure you do not add any oil to your gas as some mechanics request you do to help clean the injectors.

 

[firedog978]

There are also several good fuel additives that clean the fuel system that may help prevent fouling. I put some in occasionally, (along with my StaBil /Ethonal treatment),

 

[Scott Hammer TOXIC]

You should be treating every tank of gas. Seafoam/stabil/and Mercury's brand if you are so powered. Yamaha has Ring Free.

 

[firedog978]

Thanks Tox. I do treat every tank with the StaBil (with ethanol treatment). I have done so since she was brand new. But, are saying I should do Seafoam in every tank?

 

[Scott Hammer TOXIC]

Yes. It has 2 levels of mixing, 1 for everyday use and one as a "shock" treatment. I do the shock a couple of times a year and the everyday in everytank. Carbon is a killer and you do not want it in your motor.

 

[Greg Meyer]

I add SeaFoam every time I gas up... My mechanic would feed me my own head if I didn't.....