Does APU run off fuel?

Excuse me, but I'm a bit confused about the statement "Does APU run off fuel?" Could you please clarify what you mean by "APU"? Assuming you're referring to an Auxiliary Power Unit, which is a device commonly found on aircraft, I can say that, indeed, APUs do run off fuel. They are designed to provide power to aircraft systems when the main engines are not running or cannot provide sufficient power. Typically, they use jet fuel, similar to the main engines, but their operation is independent of the main engines. So, in answer to your question, yes, an APU does run off fuel.