Merc 9.8 wont run

My friend was given a 9.8 merc 2 stroke,he asked me to look at it to see why it was not running,first thing i did was check carberator and it was full of gunk,fixed that and it was backfiring when i tried to start it so i checked the plugs and found they were not gapped right so i corrected that then i figured i would check for spark...#1 no spark,#2 tons of spark and if i switch them around the plugs and wires work off the one coil...so my question now is it just a coil issue?or is it a control box issue and then is there a way to check it?thanks in advance