I got a 2000 blazer as a gift and it cranks like it wants to start but won't so I sprayed starting fluid and realised I have no spark so I changed the cap and rotor then the plugs the wires and still nothing how do I determine my problem? I'm assuming it's either the coil or the crankshaft position sensor.

 

if yu can get to the wire to the coil, check the voltage on it, if it's good, check the plug wires & plugs. if those are good, it has to be the coil.