Place them in the "ghost spots" shaped like canisters beside the pumps themselves. Don't forget to turn on the power though. --- I think we ought always to entertain our opinions with some measure of doubt. I shouldn't wish people dogmatically to believe any philosophy, not even mine.
Ya after you drop it in that spot, you also need to hit the gas pump where it says "fill canister" or something. I can't remember exactly, but I think I had to put it there and then fill it. --- Sent from my iPhone using the Unofficial GameFAQs app.