Not just all used up, but the ship’s captain didn’t even order any. The chamber however is nearly crammed full of extra fuel containers. A quick check shows that they are empty. Apparently they had the same idea you did about using up all the extra space aboard ship for fuel so as to maximize the time on a mission. These type vessels normally hold 88 tons of fuel (you did your research before starting this venture) and these modified probe bays would add another 10 tons. This vessel could remain hidden in deep space for a very long time.