No spark/ intermittent spark?

[wbcook5]

I have a mid 90s Mariner 90hp three cylinder. I have had the motor on the water a handful of times this summer with no issues. On a recent lake trip, the motor would not start at the ramp. It would occasionally backfire extremely loudly and sometimes fire but die immediately. I have tried using an inline spark tester on all three cylinders and it indicates no spark on any of them. What should I check next? Is it more than likely the stator or cdi box? I did notice that there is a gap between the plastic case and the potting on the cdi/switchbox. Is that normal? I appreciate any help.