Sounds like you need an ocilliscope and/or a digital volt ohm meter to check the various signals and a diagram to tell you what they all should be ?? That could get very complicated ... it might be something extremely simple but without some test equip how are you gonna tell ?
as for a coil only giving out spark when you turn the key on and off ... you are apparently giving it a signal when you turn the key on, but that is the only signal its getting ... when you turn the key back off you are probably removing power from the coil which makes the magnetic field collapse which makes it fire (thats how coils work)
Thats a long winded reply for: beats the hell out of me???
