Rough Idle, dirty spark plug - Tohatsu Guru can you figure this one out?

[wheresthefish]

this is what i already did, rebuilt carb - soaked in carb cleaner, changed fuel pump, new plugs.

this is what is happening, rough idle, very dirty plug only on one cylinder.

any suggestions will help, i dont know what else to look for.

the motor is a M40C.
i also set the adjustment screw on the card by fully closing it and going out 1 1/2 to 2 full turns.

 

[wheresthefish]

Re: Rough Idle, dirty spark plug - Tohatsu Guru can you figure this one out?

forgot to mention that the motor runs fine at higher RPMs. just wondering if this could be a power pack issue. Do these motors run off separate power packs for each cylinder? becuase only one plug is dirty the other one is clean.

 

[TOHATSU GURU]

Re: Rough Idle, dirty spark plug - Tohatsu Guru can you figure this one out?

Check for weak spark on that cylinder...The powerpack feeds both, but it could be bad on one side. You can run the electrical checks in the service manual to see if it is an ignition problem. After that you are left with a either bad reeds on that cylinder or a problem in the powerhead on that cylinder.

 

[papasage]

Re: Rough Idle, dirty spark plug - Tohatsu Guru can you figure this one out?

I had a probablem with a johnson some yesr ago like that .it had a ex-haust leak under the cover . but it ran good with the hood off . ex-haust has no oxygen in it . JUST A IDEA