Your issue is Angel's mods. They remove the fuel value from Hydrogen.
or maybe replaces the results of the electrolyser with gas-oxygen and gas-hydrogen, an angel specific version of fluids that contain the prefix gas or liquid to distinguish between the two states.
I've heard that there's a converter entity that creates bobhydrogen that has a fuel value... though I'm not sure if this is actually true or not.
It's been a long time since I've looked at his code, I just remember that's what the issue is, because it comes up a lot.
