How can i check my injectors to make sure there firing?

I checked the fuel pressure VIA shrader valve on fuel rail and i got about 45 PSI

My 350 TPI is still not running and im not sure if the injectors are firing

 

Plugging a noid light into the injector harness will tell you if the quad driver in the ECM is firing the injectors. You can pick up a decent one at the local parts house for +/- $20. You do NOT want to use a regular test light though, it'll fry the driver in a heartbeat and then you really will have issues with the injectors