Some things to try:

1) Take the coil primary wires off and on a few times to clean the terminals (this one cost my daughter an $85 service fee).

2) The next time it won't start, try rapping the Fuel relay (white plastic case) on firewall above passenger's toes. The felt hush panel has to be dropped for access.

3) Access the fuel relay and hold it while turning the Key ON (don't crank yet). You should feel/hear the click of the 1st relay (there are 2 relays inside). Then see if you feel/hear a 2nd click while cranking.

If no 2nd click, there will be no Fuel operation. Possibly due to an Ignition problem. (Ignition trumps Fuel.)

Almost forgot—the infamous 25 amp blade fuse near the coil, Check the fuse, the holder contacts, and the wire to the battery + terminal. This is the Main FI fuse.
It's a prime suspect if you don't get the 1st Fuel relay click when turning the key ON.

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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.