1997 Chevy Blazer turns over but wont start

Have a helper crank it, while you visually check for spark at the plugs. If you have spark everywhere, use a gage and check fuel pressure. Some of the national brand autostores used to loan out a fuel pressure gage, if you don't have one. To check for spark, you can pull a plug wire loose, use a known good plug or spark tester in the boot, ground metal part of tester to metal part of engine, engine cranking, watch for spark.