Plumbing issue's got me stumped

time2roll wrote:

ADK Camper wrote:
I have a plumbing issue that I just can't figure out. When using the on-board fresh tank, the bathroom cold water faucet sputters like there is air in the line. No other hot or cold faucet has this problem. If I connect to an external pressurized water line, there is no problem. A possibly related issue is that after the pump reaches pressure and turns off It will hold pressure for a long time, but occasionally the pump turns on and runs continuously, apparently unable to fully pressurize the line. Opening and closing any faucet, even for a moment, causes the line to fully pressurize and the pump turns off. I cannot find a leak anywhere. So can anyone offer a theory that can account for this rather strange set of observations.

Ok here is my theory...

The pump does not pressurize because it is pumping air. This is very inefficient and the pumping stalls so the motor runs continuous. Open any valve and some water flows and the pump primes again with water and pressurizes the system and is able to turn off.

My theory is the few air bubbles getting into the system rise in the pipe as the water flows past the sink faucet. Now you have the sputtering.

The real issue is a tiny air leak in the connection from the pump to the tank. Possibly a leak within the pump itself. Or the long shot that the water has a lot of dissolved gasses and some gas is coming out as bubbles due to temperature change.

That is all I got. Good luck.

Thanks for the thoughtful, detailed response. I checked the winterizing valve and the filter on the input side of the pump. I cycled the bypass valve to ensure it was fully in the "normal" position and tightened the filter. I could actually tighten the filter's basket about a quarter turn. PROBLEM SOLVED! Thanks again for your help!