I have a Dodge D200 440 commercial truck with 2 gas tanks and one filler sprout? Dont know how to check if both tanks work? The tank behind to seat is the tank Im filling now because when bought truck got home and seemed to run out of gas and added 5 gals to tank under truck unaware, then added fuel to other tank and started right up. There is a switch in the truck that says aux tank, but does nothing when I pull it? is there a electric pump for this tank?