I bought this Blazer and was told it only needed shift solenoids. I changed those. She ran for about a week and then stopped. First couple days I had to purge the motor before cranking and she would start right up. That eventually stopped working. Had her code checked, they said crankshaft position sensor. I changed that. Still no start. I'm fairly new to mechanics, it was more my husband's hobby and he didn't like apprentices. He's gone now so its my job now. I just need some pointers folks. Thanks

 

Go in order below and stop if a problem found. Report results.

1) test fuel pressure (loaner fuel pressure gauge from local parts store). Should get about 60 psi with KOEO for 2 seconds when key is first first turned on and hold above 40 psi pressure for some minutes.
2) test for spark at coil (spark plug on end of old spark plug wire plugged directly into coil, and spark plug grounded to metal on engine) - then crank and watch for spark to jump the gap.
3) test for injector pulses from PCM (big injector connector disconnected and noid light from local parts store across terms for one of the injectors) - then crank and watch for noid light to pulse.