The two saddle tanks should be draining down at the same time, and should have close to the same amount of feul in each, so not sure but you may have an issue there. As for the labeling, The sender for the rear (saddle tanks) is only on one of the tanks, another reasonas to why they drain down together. The main tank under the seat also has a sender. Yes the tank selector on the dash is only for fuel readings Left is main or the the under seat tank, right is rrear or the saddle tanks. Esy way to rememebr the seletor valve in the back is the arrow is pointing at the tank(s) you wish to use. Left points fwd (towards the main tank) Right points to the side of the boat (saddle tanks). Yes id agree with coming down on the JP.