Welcome to the BB, mainline!
Looking at the wiring diagram that's located
here the green/black stripe wire that powers the coil with battery voltage should run uninterrupted from the top of fuse #6 to the coil + terminal. First thing to do is to check/clean the wire connection at the top of fuse #6. If it's OK, then either the wrong wire is on the coil, the wire is broken somewhere or perhaps the PO installed an alarm with an ignition interrupt.