1974 mercury 7.5 hp 2 cycle

[Mason Sowell]

Has the two red coils behind flywheel, if a coil is going bad or bad will it spark internally? It has spark at the plug but not as big of a spark as the number two cylinder, drops to one cylinder at idle then other cylinder comes back at mid range point through to wot. Any info would be appreciated! Thanks

 

[Texasmark]

Re: 1974 mercury 7.5 hp 2 cycle

Yes it could spark internally. However, if it did, it wouldn't take long for the malfunction to grow to the point where the coil would never work.

I had that exact model engine once but it has been a long time ago.

If you have CDM's (capacitor discharge modules) attached to your plugs, first order of business would be to swap them and chase your bad spark. If it doesn't follow the CDI then your stator must be bad. When I say swap, swap the module, obviously the plug # it's output is attached to, and it's inputs.

HTH,

Mark

 

[Faztbullet]

Re: 1974 mercury 7.5 hp 2 cycle

Swap the coil position and see if problem follows the coil, if so coil is bad. If problem stays with same cylinder it most likely a switchbox. If it was stator both cylinders would be weak as they share the same voltage from capacitor......

 

[Mason Sowell]

Re: 1974 mercury 7.5 hp 2 cycle

Thanks texasmark & fastbullet. I'll give it a try. I feel it's the coil, I'll swap the coil positions this afternoon, it will go about two hundred yards on one cylinder then the other cylinder will kick in, even then I feel it's not to it's full potential. Gonna go ahead and get both coils, kinda like tail lights, one goes out the others not far behind. Seeking optimum performance! For what it is! Thanks again!