My Coachmen when they were still just Coachmen had a fresh water tank issue also. Luckily I found it while running some wire back to the rear for a back up light.
The tank was just hanging by the hose running to the pump and one corner hung up on a brace.. No idea how long it had been like that as we rarely used tank water. It looked as if they didn't have the right tank when this particular trailer came down the line so they just stuck another one in there and it was only held up by a piece of particle board. Ever seen wet particle board under a load? I fixed some angle iron under the tank and went on. The trailer was over a year old before I discovered the problem.
