inertia switch

Battery has a full charge? The starter motor cranks good? Did you check for good spark at all the spark plugs? Did you use a gage and check proper fuel pressure? Did you check for fuel injector pulse. You need to check those with engine cranking. Does the distributor rotor turn when you crank it? Do you have cylinder compression? Your obd1, you should be able to check some codes, yourself, if there are any? To check codes, use jumper wire between A & B terminals at the datalink connector, then turn key just till the dash lites come on, no further, then hopefully the mil on the dash starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

Just to add, you don't have a bump switch like Ford does.

If you havent tuned up the vehicle in a while, even if you have spark it might not be enough. I just went through this with a 97 S10. had fuel and spark, but spark was kind of yellow and weak. put in a new cap and rotor and boom, started right up. also, If you want to check the computer for 2 digit codes as oilyspill suggests, then once you have jumper wired terminals a and b the check engine light will flash. it will flash 12,(once, pause then twice). it will flash 12 three times then if there are codes stored it will flash them next. It will flash them 3 times also. Let it go through the whole cycle. if there is more than one code stored you will have to pay attention until it goes back to flashing the 12. that means its done and it has shown you all the codes.

there are some good youtube vids on "how to read chevy obd1 codes"