You ignition switch's input comes from the battery and is hot all the time. The output (switched) side is only hot when the ignition switch is turned on. If you wired your gauge to the hot side of the switch it could be the parasitic load you're looking for. The easy way to tell, if the gauge and sending unit are working, is if your gas gauge shows the correct level of fuel in your tank "with the switch off". If it's wired correctly it will show empty, if it's wired to the hot side it'll show how much gas is in the tank. If it's showing above empty with the switch off move the wire to a switched terminal and that will remove the load.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.