Water Pump Sputters and has shore water running through it when off
I noticed my empty fresh water tank was dripping water from the open drain (leave it open for winter). We're hooked up full time and today I chased down where the water was coming from- the feed line from the water pump. I verified this by disconnecting it from the fresh water tank and watching water drip for over an hour. It filled up a gallon jug and then some. Since the pump doesn't have a reservoir that large I chased it down.
First I filled my fresh tank and turned the pump on to see if it was working properly. That's where I'm stuck. When I have the tank FULL (checked many times) and turn on the bathroom sink faucet, the pump will charge the lines, get the air out, then sputters and pulses. It does this with hot or cold water and does the same with any other faucet. I unscrewed the in line filter, made sure it wasn't clogged, bled the air out, then tried again. It wouldn't stop unless I open another faucet (two or more at the same time). With the Bathroom and Kitchen sink on at the same time the pump runs like new and there is no sputtering at all. When you turn both faucets off the pump shuts down. The only explanation I can think of is the pump thinks its providing too much water and backing itself off.
Next problem is when I drained the fresh tank and left the cap off (absolutely no water in the tank), made sure the pump was off, then turned the shore line supply back on. I went back to the pump and heard water running through the lines with no faucets open. To check where it was going I removed the in line filter on the pump and watched water pour out without stopping from the tank side of the pump (backwards). This is how my fresh tank was getting water in it and dripping.
We had a cold winter but I made sure never to let the pump get too cold by leaving the cabinet door open and checking the temperature throughout the cold spells. The pump is under my bathroom sink in the living area. Lines never froze and everything has gone smooth.
For the short term I rerouted straight to shore water and bypassed the pump.
What is wrong with my pump? Any ideas?
My TT: 2013 Cherokee Grey Wolf 28BH