Now is the time to find an auto-electrician or perhaps a friend with electrical experience and the necessary tools & test equipment - electrical troubleshooting has it's own peculiar challenges & methods.
You can try Ack's FAQ for a wiring diagram, I know he has them for the 1.3's I don't know if he does for the 1.0's, you haven't told us where you are, but a US market 85 Samurai would have been a 1.3, not a 1.0, which could also be a problem when it comes finding a diagram that matches the vehicle.
Check your distributor, if it uses breaker points, check the ignition coil for a 12V feed, and if there is none work your way back to the ignition switch - the fact that you can crank the engine suggests there is 12V power to the switch, but it doesn't mean that the switch is feeding the ignition circuits when it should, if there is power on the ignition circuit at the switch, then the problem will be downstream from the switch, possibly a broken wire or intermittent connection, possibly near the fuse panel.
I strongly recommend you find either an experienced auto electrician, or someone familiar with the Samurais to help you.