Re: 2001 Johnson 150 hp has 1 oily, black spark plug
O K,
Here's the final scoop. I made an appointment at my local Johnson / Evinrude dealer and took the motor in. The tech did all the standard checks and confirmed much of what has already been posted. He said that #6 cylinder is where the pulse is derived to operate the vro oil mixing pump. He said he searched farther into the vro oil mixing pump and found a diaphram with a hole in it that was letting gas run back through the pulse line to #6 and soaking it, therefore causing my overly wet and carbonned spark plug in that cylinder.
The VRO failed other tests on the bench, so he replaced it with a new one. $750 (Parts & Labor), and a decarb later, my motor is once again running like it is brand new, if not better. My top speed is 2-3 mph faster and it's cranking out 300 more rpm on top end and the vibration is gone.
!
O K,
Here's the final scoop. I made an appointment at my local Johnson / Evinrude dealer and took the motor in. The tech did all the standard checks and confirmed much of what has already been posted. He said that #6 cylinder is where the pulse is derived to operate the vro oil mixing pump. He said he searched farther into the vro oil mixing pump and found a diaphram with a hole in it that was letting gas run back through the pulse line to #6 and soaking it, therefore causing my overly wet and carbonned spark plug in that cylinder.
The VRO failed other tests on the bench, so he replaced it with a new one. $750 (Parts & Labor), and a decarb later, my motor is once again running like it is brand new, if not better. My top speed is 2-3 mph faster and it's cranking out 300 more rpm on top end and the vibration is gone.
!