Picked up my 87 240 DL about a month ago. Love the brick. Runs great, purrs like a kitten, ... EXCEPT, when the weather is damp. Runs fine in the heat, runs fine in the cold, ... snow, rain, no problem. But once 2 weeks ago and again this morning, it's misty/foggy/damp outside and she won't catch. Turns over fine, ... can hear the pump, ... lots of battery power, ... looks like no spark. I'll be pushing it into the garage this evening.

I'm guessing a "fire" problem, ... coil, or distributor area getting wet with the damp air. Any suggestions as to:
1. is this an accurate conclusion?
2. how to test/check the spark components

Any help would be greatly appreciated. Thanks all.