While preparing the trailer for a trip without hookups, I filled all the plumbing via city water port, flushed out all air, then added water to the fresh water tank to 40% level for testing the pump. The pump ran, but wouldn't stop & would not reach full pressure, even after several minutes. I immediately checked everywhere I could think of for leaks, but found none, including the valve area, mixing valve, all reachable fittings behind toilet, & under trailer. I could open the fresh water tank drain valve & get water. Checked all valve settings - they were in the correct position. I checked the pump filter - clean; removed the pump input hose & was able to blow air into the fresh water tank without resistance; then removed the output hose & attached a short piece of hose & was able to pump water into a jug. Reconnected pump hose, and turned pump back on. Within about 10 seconds, the pump achieved full pressure and stopped. Everything was back to normal, but I have no idea what the problem was.
-Brian in Chester, Virginia
TV: 2005 Toyota Sienna LE (3.3L V6)
RV: 2018 [email protected]
320S, >60 mods