Plumbing- where is the "external water supply source valve"?

Doug, When you do install the new pump, place a rubber pad under it to help quiet it even more. Some people have used computer mouse pads for this. I used a piece of 1" thick foam.

Bob

When you replace it tear into it and see if there is debris blocking it. I have heard of this years ago where the pump ran fine after it was cleared.

If it froze and cracked the other place you will see a problem is in the toilet valve, it leak externally (to the toilet but inside the camper) if it also froze and cracked. I've had to replace both the plastic pump and the toilet valve because of this. The toilet valve at least will show the problem with either the pump working or external hose pressure to it so if you have been using a hose you should be good.

HiLo problems

If your pump has a clear plastic filter screen on the input side an if water froze in it you may have a crack in it and the pump will suck air thru the crack and the pump will not self prime. Check that out.

For our water pump to work the "valve" that is on the city water tubing is turned and not straight or in line with the tubing. System then pressurizes. Bob's sounds similar to our unit.

If I have to remove the hot water tank or fiberglass wall...

Thanks Jim L, Elaine and Bill,

Jim L,
It turns out the clear plastic filter screen on the input side is OK, and I took it off the old pump and put it on my new pump which works well in my test setup. Wiki shows me how the pump works- https://en.wikipedia.org/wiki/Diaphragm_pump

I took it apart last night, but couldn't see anything obvious. Anyway, my new pump works and the remaining problem is the water leak at the city water flange.

Elaine and Bill,
With the board under the couch removed (it was screwed down) to replace the pump, I could see the tubing and diagrammed the fresh water and city water plumbing. There are no valves- lots of elbow and two tee connectors- but no valves. Without removing the hot water tank I can't get to the tee connectors and loosen the tubing so that I can replace the leaking elbow connector inside the city water cutout.

Question. I may have to remove either the hot water tank or the outside fiberglass wall in order to replace a $4.00 part. How difficult is iy to remove the tank or the outside fiberglass wall where the city water cutout is? What else should I knon before attempting it?

I can't imagine this-maybe a stop cock is a better word than valve. Fortunately we have never had difficulty. We fill through the city water inlet on side of camper, may top off using the manual fill with a portable water tote. Our stop cock is straight using city water and turned to pressurize system when using water tanks. One can hear this process. I would think "stop cock" would be very close to the pump set up/city water tubing connecions. Also the antifreeze stopcock needs positioned to the pump for our unit to pressurize/work.