Fresh water tank/pump

[sreigle]

Harry, if I recall, the tanks are shallow but long, so 4 gallons or so might not be that far off.

Any chance your pump is sucking air and losing it's prime that way? Like maybe a loose connection or a hole in a line? Otherwise, maybe the diaphragm in the pump has a hole in it? There used to be repair kits to replace the diaphragm available at RV dealers but I don't know if they're still available.

Good luck. I'm curious what you find is the problem.