No spark on one cylinder?

[KeithV]

I have a three cylinder 50hp Merc. (1986-90) with no spark on one cylinder, was told it may be the 'switch box", any other thoughts/ideas before I spend hundreds on that part? Cheers!

 

[achris]

Re: No spark on one cylinder?

More likely a coil or trigger. You have 3 coils on that engine, swap the dead one with a good one... See what happens.

Chris......

 

[chum1]

Re: No spark on one cylinder?

here is a couple shots of what i just found out on mine, I think it has a similer ignition system but 4 cyl.

1st pic:a weak or no sparky on one plug
2nd pic:swapped wires on these two coils and the problem changed to a different cyl. (spark plug) thus the coil was good.
3rd pic: found a loose connection on terminal end, you can see where it has been arcing. tightened that terminal and the spark returned to the plug

Good luck