2006 3670RL fresh tank drain issue

[EllsworthToohey]

Here is a new one I discovered today. I see what can only be the Fresh Water tank drain valve under the rear belly of the trailer. When I discovered it it was in the open position. This was after I filled the tank with the hose till it over flowed the fill port. Level Sensors read full. I have never been able to get the water to run by pump, and when filling never heard any water rushing out the drain.

After reading some Fresh water pump issues here, I thought that maybe with that valve open it allowed an air leak that prevents the pump from pumping. So today while working on the Galley Tank, I filled the fresh tank again and tried the pump. Nothing. I opened the drain valve and NOTHING!!! It did not drain. It let a few droplets form but no rushing of water! I shoved a small stick up thru the valve and it feels like maybe wasps or something might have crawled up there when it was left open and sat in storage for a year or more. Does this sound likely? I have found lots of wasp nests all over this trailer. Both Paper wasps and mud dobbers. I cannot think of anything else that would prevent the fresh tank from draining. Now I am wondering if they got up into the tank itself!!!

[Carl n Susan]

Based on filling the tank until it overflowed and the gauge saying it is full (the fresh water gauge is the only one that really works) I think there is a blockage of the drain line. A picture of the line showing its location would help verify it is actually the fresh water tank drain, but there wasn't much else back there in 2006.