Re: Inflatable tender exasperating valves
with the valve cap off, most valves have two positions, "open" and "fill" in which mode, air going in pushes a seal open and otherwise, the pressure in the raft pushes the seal closed. Usually a quarter turn to switch.
If is is just leaking, there may be debris, but that's doubtful if all valves are problematic.
Pure liquid glycerin will sometimes seal leaky valves, but probably not if they leak that badly.