I had kinda similar issues with my 91. On hot days I would not get a start, in cool mornings/nights I could get a start.
My issues was that the main relay had hairline cracks in the solder, and was not switching on the fuel pump. I used a big-ish soldering gun for plumbing, and reflowed the joints with some new solder. This was .. 8 years ago, and still going. I could have replaced the main relay, but IIRC, it was $75 + tax.
As to your issue, it sounds like a shorted wire(s), or bad connection at the relay, fuel pump, or wire(s) in between.