Engine cranks over, but won't start.

After driving for about 30 minutes or so, I stopped at a gas station to get gas. I turned the car off, and when I went to turn it back on, the car cranks, but will not start. After trying again, same thing. The third time, all I get is click click click. I thought it may be the battery (it was honestly pretty old). I replaced the battery, same thing. The car cranks just fine, but will not start. I have had someone help me to check, and can I can hear the fuel pump running when the key is turned, so I imagine that is working fine. So now I am at a loss. I have a '91 Dodge Dynasty, and I have no clue as to what it could be, or if the car is even worth the cost of repairs to fix this problem.