My little GL has decided to start blowing the ignition fuse. Unplugging the distributor Ignition Control Module allows it to crank without the fuse dying, unplugging the secondary Coil still kills the fuse while cranking. I have replaced the ICM, but still have the issue: if the engine fires and tries to run (3 seconds or so of Spark) then the fuse blows. has anyone had this issue? What else could be grounding in that two wire primary coil circuit during Spark? Coil has reasonable resistances, primary and secondary.

On my 87 Brat I had the ignition fuse blowing on start up or if I hit say railroad tracks just right. Took a lot of searching, frustration and I found it to be a very thin wire (18 or 20 ga) at the back side of a wiring harness under the dash and behind the instrumentation. It had barely rubbed a piece of metal until it cut it. Then a bump or something would make it touch and no go, blown fuse. Seems the only thing I gained (besides not blowing fuses) was one light near the speedometer or tach (can't remember which) would now light up when the headlights are on after I fixed it. Yours does sound a little different but sadly that is the way are! Good luck!

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Thanks, Bratman2. I am guessing that a wire is touching somewhere. I looked at the distributor, but two wires don't leave many possibilities. It is only when the thing goes to fire with full circuit connected that I get a blown fuse, thankfully it is not intermittent. I am now starting to wonder if the problem wire is downstream from the module somewhere.

 

I have found the problem. After reviewing the wiring diagram supplied by a friend with AllData access, I saw that there is a separate branch of the Ignitor/Distributor circuit leading off to the Automatic choke. The wire had come in contact (direct ground) causing my fuse to blow. 

Aha, is the electric choke connected and functioning or was the connector just randomly hanging about in the engine confines?

Good that you found it

In this case, the auto choke I had removed and replaced with manual. For 50k miles it had sat right where I intentionally left it: and then one day.. .  I just hadn’t considered that it was in that circuit, AND would wait until firing/running to eat the fuse.