Hi new guy here

[Timloy59]

I have a 1978 70hp mercury not firing on 3rd plug checked coils it's good compression is 120 on all 3 heads can anyone point me in the right direction

 

[fastjeff]

Swap two coils around and see if the problem follows. Make a wiring color diagram FIRST or you'll go nuts.

Jeff

 

[Timloy59]

Swap two coils around and see if the problem follows. Make a wiring color diagram FIRST or you'll go nuts.

Jeff

OK will try that tomorrow thanks a lot for help

 

[Timloy59]

Did try that today and did do what you said it would thanks looks like it the switch box thanks jeff

 

[fastjeff]

If the same plug still does not have spark, switch box or possibly the trigger coil. If the problem followed the rewiring, it's the coil.

Jeff