Need help bad, first of my 2000 Chevy blazer Is a 4wd 4.3 4door. It has a misfire on po302 and po452 evap code. When testing injector harness while cranking the motor, test light don’t blink on any injector. Just stays lit. Need help trying to figure out why its not pulsing like it’s supposed to. Any help is great appreciated in advance.