water pump problems

Thanks for all the suggestions. It is definitely on the inlet side. I have no idea what happened but I have leak right at the top of the fresh water tank. I am thinking where the fresh water line enters the tank. I had two thirds of the tank filled and no water leak. When I filled it to the brim a little water leaked out. I checked the pump by running water through the winterizing hose and it worked fine so.... I replaced the pump for no reason. :( Works fine with city water inlet though.

On some setups, and this problem sounds like one of them, the exit point of the tank that leads to the intake of the water pump, sometimes have a pre filter the shape of a nipple that is part of the exit plumbing. This nipple is a screen material probably stainless steel to eliminate corrosion. Over time the inside of the water tank develops a skin like material that is not harmful, but clings to the wall of the tank. Constant filling and draining can can shake loose some particles of material as the water level drops and float to the discharge point of the tank plugglng the screen on the inside of the fitting. Removing the fitting at that location will reveal I think, the culprit of your issue. It will come out as one piece and is easily cleaned.

If it keeps gurgling that means it is sucking air.. Now fact it will gurgle for a long time when you first charge the lines but ... .... if it's sucking air it will gurgle forever.

now why would it suck air
The most likely cause is the inlet strainer on the pump. but you'd have checked that when you replaced the pump Still check to insure it is properly sealed and not cracked.

Then inspect the suction line ONE option.. on my RV the fresh tank drain valve is "T" connected to the suction line. did you remember to close it

As others have said some rigs have a 3-way valve called a "Winterizing" valve that changes the suction line to a hose that can suck pink stuff out of a bottle.. If you have such a valve is it properly set.

Next is a pin hole in the suction hose or a mouse hole.

Finally and this one is rare.. My tank has an outlet strainer as well as the inlet strainer on the pump.. it can get "Slimed up" (in theory, never seen it happen) or otherwise clogged (Again never seen it happen).

On some RVs if the water is set to "city water" and you turn on the pump it will just pump water from the fresh water tank back into the fresh water tank making gurgling sounds and not sending anything to the faucets. Discovered this helping a friend de-winterize his Class A Dutch Star.

RV water pumps are simple diaphragm pumps......won't pump air/faucet has to be open for pump to prime and move water & expel the air is system

Two pumps doing same thing (not priming) ......then you have 'air leak' on suction side of pump(s)
Strainer gasket, pickup hose clamps, winterizing valve open/leaking etc
Problem is on suction side.

Sounds like you're sucking air instead of water from the fresh water tank.

Take the line loose from the discharge of the pump to make it easier for the pump to prime.

You might need to connect a hose onto the suction side of the pump to get it to pick up water after 4 years of setting idle. Once it's primed, connect the suction side back to the water tank to see if will pick up any water from it.

Can you put a clear hose on the line from the fresh water tank and use your mouth to draw water up the hose to verify the line isn't cracked and drawing air instead of water?

Assuming it has not sprung a leak & is pumping water somewhere it is not supposed to, start again.

This time leave all the taps closed & the water heater bypass on (so water cannot get into the water heater).

All being good the pump should pick up suction & pressurise the air in the pipes then shut off. Open cold taps etc. one at a time. A blast of air comes out then water. By the time you get to the next tap the pump should have repressurised the system. Open the bypass valve & fill water heater & do the tap routine.

Still no luck? Check the inlet side of the pump. Real easy for that not to be airtight if it was removed for winterising.

Inlet OK? Check the output side of the pump by slackening the fitting & turning the pump on.

Still no luck? You did put enough water in the tank didn't you? Next is the pump itself. Could be a split diaphram. Replacement kits available for some pumps. Might be less hassel simply to get a new pump.

I hope a squirrel didn't eat a water line.

sorry didn't read far enough.

Do you have a winterizing valve and is it in the correct position?
What position is fill valve in if equipped?