In both the R22 and the R44, the main and aux tanks are connected by a cross-feed pipe - unfortunately I don't know exactly where the cross-feed is (note to self - find out!). Fuel is gravity fed to the engine.
Since the aux tank is smaller than the main - 18 gallons compared to 31 or so for the main - and the bottom of the aux tank is higher than the bottom of the main, in normal operation the aux tank should empty first then the main tank should empty. Theoretically, when both tanks show empty the fuel low light should come on, i.e., you're out of fuel.
Since your post is half-completed, perhaps you could expand on the exact nature of your problem ?