As said, could be the pump. Try stomping the pedal to the very end even faster a second or 2 after the key is turned. It's a learn by experience technique. You might not get a code relating to the actual problem if it is a pump. The check engine light could jave come up b/c of sensors being affected by a dying pump, like the O2, knock sensors, or voltage.
Only other thing I can think of is a coil going bad and taking the computer with it. Lets hope for the pump. As said, try to hear the pump on the cover in the trunk and ypu can also attach a gauge to the valve along the fuel rail.
Good Luck.