I am a novice mechanic and need some help. I have a stock '89 5.0 EFI with the stock wire harness and nothing removed. I turn the key and can hear the fuel pump turn on engine cranks but will not start. I was able to verify fuel to the fuel rail. I have 12 volts at on the red wire to the injectors. I have triple check timming and every thing is right there. I think the injectors are not opening. How can I verify that.