Simplified schematic:
Does that mean a schematic with bits missed out? If so it is useless and we need to see a complete version. One that includes the capacitors that you have put across your 7805 chip.
Do you know how much current the motors draw?
Conclusion: it seems that somehow these pumps mess up the power supply to such an extent the voltages appear to be there, but the current not.
You need to look at the voltages on an oscilloscope to see if the regulator is oscillating.