You might want to cycle the fuel pump about 5-10 times(turn the key to the on position then off) until you hear the sound changes (lower whine).
NEVER LET YOUR CAR RUN OUT OF GAS!!!!! no shi. huh
If you continue to have problems, you can force the pump to run 100% of the time (when key is on) by connecting K31 20 BR/VT (brown/violet stripe) wire in the plug harness (next to the amplifier in the trunk) to ground. The PCU switches the pump on by grounding this lead.
The fuel is used to cool the pump