After hours of trying to figure out where all my power was going, I found out that I inadvertantly had a Mekanism Universal Cable next to a wooden fluid pipe that was pumping liquid. I have tested this on a single player server with just a wooden fluid pump hooked up to a tank. It happens with both Fluxducts from Thermal Dynamics, and Universal Cables from Mekanism. The wooden pump does function from this energy, but it is using approximately 1 million RF/sec.

Buildcraft 6.4.11
Buildcraft Compat 6.4.2