I have a 2005 chevy cavalier for some reason my car cranks but doesn't start but sometimes it does start.
some things that are going on

1. when the key is turned to the on positon my headlight icon comes on and goes off by itself also the fuel pump relay under the hood keeps vibrating/buzzing noise
2. car cranks but doesn't start
3. fuel pump only primes sometimes not all the time
4. when the key is turned to the on position as mentioned above on 1 that happens on top all the lights comes off and thn shut off every couple of seconds

need help I have already changed the fuel pump and still doing the same thing

What brand of fuel pump did you use? Did you check for leaks? Did you check the fuel pressure?

Pretty much ever car has all the lights come on when you first turn the ignition to the on position.