Intermittent spark

[georgedexter]

I have a 1996 90 HP evinrude 4 cyl. It will run smooth then without warning lose spark on one or two cylinders. These are both on the same side,over and under. I have checked the plug wires and put in new plugs. Then I used a clear spark checker to ascertain the problem.
Spark cuts out and returns on its own time. I don't want to start buying parts until I get some opinions. Does it sound like power pack? Is there more then one power pack,is it hard to test,and so on? Thanks Georgedexter

 

[petryshyn]

Re: Intermittent spark

try swapping coils from one bank to the other and see if the misfire follows. This will atleast rule out the coils.
Then the old rule applies.....give the pack what it needs, if it doesn't function, replace it. It needs an appropriate charge voltage and trigger voltage and good wiring. You will need a DVA, voltmeter, and a manual to decide whether its getting what it needs.
The other method is to take an educated guess and replace parts one at a time. Pack, trigger coil etc.