Why would the coil not spark?

Usually the first thing that I would check is a bad ground of the coil itself. Now if that does not work then you should let a professional do this but it is an old trick, but power up the coil manually by grounding the bottom of it to the car and then taking a wire from the pos side of the battery touch the batt post of the cap. You olny need to do this for a second. Then take the wire away from the battery and DO NOT TOUCH THE CENTER OF THE CAP!!!! but ground out the top of the cap. YOU WILL SEE A SPARK!!! if you do not then more than likely the cap is breaking down and not holding a charge. A coil not sparking could be many things like a ignition module it could be the crankshaft possition sensor or camshaft position sensor