On our 2001 Marquis the water tank is filled by pressure from the city supply. We simply turn on a fill switch, the tank fills, the valve automatically closes and we try to remember to shut the switch back off. We also have a separate gage that weighs the pressure of the water in the tank and shows on the coach information panel the gallons in the tank.
Recently, the shut off is occurring much before the gage reads full. I know that the sensor for the gage is a weak link and have replaced it once in the past. I also know that I can recalibrate the system and perhaps get the gage to read correctly. I am not in a good position now to drain, fill, empty and measure to really trouble shoot and recalibrate if necessary.
What would be very helpful to me at this point would be to know how the shut off switch works. Is it a simple float switch like the toilet shut off on the black tank? Can it shut the water off prematurely when the coach is level? If it is just a short stroke float switch then when it works, it should always work fairly accurately. Just wondered if anyone has seen it or might know how it functions.