Hey, I've found a bug... I've built a small contraption to replicate the bug: https://www.dropbox.com/s/ks4ng66ccyu22t0/KER-Bug.craft?dl=0 I know it's a weird structure, but I used it in a heavy-duty Jool mining ship... The delta v shown by KER is 0, but the fuel flow overlay is OK, and the engine works.