The hydro boost brakes have a funny mushy feel in the driveway but driving they feel fine so that may or may not be your problem, and those switches do like to leak. Many on this board seem to feel that if the primary (not main) pump in the tank isn't working it will lead to premature main pump failure, but that has not been my experience. I'm sure it does have a function but as far as I can tell it allows you to run the tank a bit lower before you suck air and run out of gas. Mike W.