I have a 1986 15 hp Johnson that I am having a hard time starting. The spark air gap according to the book is 1/2 inch. I am getting about 1/4 at the most. That is when I pull it as hard as possible. If I pull it half heatedly I get no spark at all. The charge coil ohms out at 540 ohms. Sensor coil is 40 ohms these are in spec and so are my 2 ignition coils. I really don't have a way to check the voltage. Could my charge coil be weak even though it ohms out ok? Anyone out there have any suggestions?