Water Pump Continues to Run Very Slowly and Won't Shut Off
Just returned from a 4-day trip to Yosemite and had a near disaster in our Motorhome. Most of the time the water pump will pressurize the system and shut off like its supposed to do. Occasionally though, it will pressurize the system, but then will slow to about 1-3 revolutions per second and continue to run until either I notice the voltage drop or I hear/feel it. And of course, when the pump is at this point it is using the maximum current.
The H2O pump has always had this problem and I have usually caught it. This time however, I believe one of my kids left the pump on as we were leaving for the day and I didn't notice it. When we returned I couldn't figure out why there was no water at the faucet, the water tank was 3/4 full, the pump light was on. I went to the basement to cycle the fill valve to clear air and make sure the pump was primed. When I opened the basement door I noticed a slight hot electrical smell. The pump was very hot, too hot to hold my hand to, and the + wire had about 2" of insulation melted around it. Fortunately, there was no metal near the wire and the pump's thermal protection shut it down. The pump started working again after it cooled off for about two hours. Though my battery bank hit 11.5v, ouch! There are no apparent leaks and the fresh water level did not go down and the grey water tank level did not go up.
So, my questions are... I know there is an single adjustment screw on this pump, its a Shurflo variable speed/flow (don't know model # off hand) made in 2010. Will adjusting this screw help with this problem? If so, in which direction should it be turned? Or could this be caused by a leaky valve in the pump? If its the valve, whats the procedure to fix it?
Thanks for helping me figure this out.