We were away for our second weekend in our 2006 Autocruise Starfire. Everything ok except that once or twice the water pump started up on it's own and didn't stop until we turned on/off a tap. The pump sounded as if it had very little load on it....it was ticking away at a higher rate than normal. When we turn on a tap it ticks fast then gradually slows down when we turn off the tap as the pressure builds up. It almost sounds as if there is an air lock in the pump. But putting some water through the pump when the tap is on clears it. I can't see any leaks anywhere and the taps don't drip. any ideas?