The power is fluctuating a lot on the MFSU because the EV consumer eats 2048 EU/t. How much power are you giving it? The energy bridge also has an internal buffer of 40,000 EU and 160,000 RF.
The EU to RF ratio should be 1:4 unless it was changed in the configs. So, you would be getting 8192 RF/t if you can supply the full 2048 EU/t. But, that amount of RF is way over what you need for a single quarry. The power draw from the pump is negligible. You would need about 1000 RF/t to power a quarry at max speed. Thus, you'd need to be supplying at least 250 EU/t. You can use an energy cell to throttle the output for less energy consumption at the cost of less speed.