If you do not hear the fuel pump when you first try to start the car (Believe me, you WILL hear it!) the #3 relay may be fried. Another thing to check will be the ignition switch. These are plastic junk, and will cause the fuel pump not to engage at times. Also, check the condition of your fuel lines. You may have a pinhole leak in one of the lines.
Which wire is the hot one on the pump, red or blue? And does the car need to be turning over in order for the pump to kick on?