Three things needed for combustion are fuel, compression and spark. Try spraying some starter fluid or 1 tbsp of gas down the carburetor and see if it runs for a second. That will indicate fuel delivery problem such as clogged jets or float stuck in carburetor. If it doesnt, then you may not have spark. Pull #1 plug and hold against the block with the wire connected and see if it sparks when turned over. if good spark, timing possibly out because of cross wired spark plugs or the timing chain jumped a few teeth. These two would usually cause a back fire or popping through the carb. Last straw is to get a compression tester and check all cylinders. They should be within 10% of each other. If compression is low <60-80 psi), squirt some oil ~1 tsp or couple squirts from an oil can in the spark plug hole and re-test. If the pressure comes up, the rings are shot. If it stays low it could be the timing chain, head gaskets or valve seats. Good luck. comment back what you find or need more info
98 Blazers will not start over sue to either having a low fuel pressure or a spoilt crank sensor. Therefore, you need to check the fuel pump for the pressure and replace any bad sensors. Consult a Blazers mechanic for more help.