Spark problems

[VikingRSA]

Hi to all. I am a very newbie to the boating world and have recently bought myself a second hand boat with 200HP Mariner on the back. This motor has giving me problems from the first day. It’s a '87 200hp V6 Mercury power head on a '95 150 mariner lower unit. I have no spark on my top left cylinder but all other 5 are fine. Could someone be able to point me in the right direction as to solve this problem??

 

[Laddies]

Re: Spark problems

If you lose spark on only 1 cyl on a V/6 it's one of four things, plug wire or a wire from the switch box to the coil, a coil or switchbox

 

[andy6374]

Re: Spark problems

or coil ground. Classic culprit!

And if I am not mistaken the bias circuit between the switchboxes isn't known for taking out a single cylinder. Disconnect the bias circuit (white wire) and if spark returns to that 1 cylinder than it was the other (seemingly good) switchbox that is to blame. Replace both and replace with CDI/Rapair.

 

[VikingRSA]

Re: Spark problems

Thanks guys!! will check it out8)