I just recently had an aux fuel tank installed. Since then I have been having a problem getting a complete fillup. The gauge indicates full until I ride a few miles and it drops down one or two gauge markers. I suspected a vent tube issue but I took off the seat and the vent tube is routed properly and doesn't show any signs of being kinked. I've tried the slow fill, wait, then top off process but either that doesn't appear to work or I'm not doing it correctly. Can anyone with a aux tank give me some help. P.S. I have a thorough understanding of the theory of how the aux tank is supposed to work. I just need help on the practical side, getting it to work.