1992 Chevy Astro wont start! Please help!

It akes three things to run an engine. Spark, fuel, and comression. If you are getting fuel it's probably spark. See if you are getting spark from teh coil to the dist cap. And then see I you get it from the dist cap to spark plug wire. If not it's a problem inside the cap, which you can get a cap and rotor. If not it canbe the switch inside the dist. Or the ecm.

Fuel is supposed to return to the tank. That's the way fuel injection works excess fuel is returned to the tank. From what you described it looks as if you aren't getting the spark to run the engine. Check what i've said and also check forcodes. Put a paer clip between A&B and watch the service light flash and count them it will flash once then twice for code 12 then it may go to other ones. You have an OBD1 system so go backon the site to lead you what may be wrong. Although if you have disconnected any sensors it will probably give you acode for that.