Check the grounds from the battery to the body, and the body to the body of the coil/ic igniter. I had a similar problem. I solved it by running an additional ground cable from the point on the body where the battery ground goes to the starter mount bolts. This gives the starter a much better ground than going through the cheesy strap ground that has gotten corroded and nasty. Mine would crank all day but no sparky. It would push start though.