No, that's almost right. There are two types of fuel - Jump fuel (used every once in a while) and "Normal" Fuel. Normal fuel is used whenever your ship is accelerating or maintaing a constant speed. You have a finite amount of this fuel, and your almost consant usage of it is offset by your magnetic scoops intake of various free-floating particles. This intake also slows you down, keeping you from accelerating infinitely. This fuel will concievably run out - but only if you've turned your scoops off. Your afterburners use energy because they're running large amounts of power through the remaining un-burned fuel coming from the engine exhaust. Thus igniting it, and causing additional, sudden bursts of speed. So, you've got three major resources: Jump Fuel ( Used by the jump drive), Normal Fuel (Uses by your engines and afterburners), and Power (Used by your guns, shields, tractor beams, afterburners and generated by your engines). This make sense?