I am not a pro mechanic, I started on this project z ‘75 280z fuel injected. I changed all the gaskets and realized I needed new fuel injectors. I pulled them and changed them. I didnt relieve the pressure by disconnecting the line and letting the pump pump it out. I leaked some fuel and relieved the pressure that way. I replaced everything and put the car back together when i went to turn it on it wouldnt turn on. It cranks and if i give it gas it tries to turn on but wont stay on. I think i have spark. When i have the key in the on position i can hear the fuel pump working. My gas tank currently has under a quarter of gas. And before i change all the spark plugs and wires how can i make sure if its the gas pressure or if it isnt getting enough gas. I changed the fuel filter too. What should i do to run diagnostics? Thank you!