fresh water tank Water Systems

[gpafox@att.net]

My 04 Monaco Windsor fresh water tank is not getting water to the water pump.  I always thought the water from the tank was gravity fed to the pump which is two bays away from the pump.  For a long time while traveling I would get a vapor lock and would have to open a release valve and let a little water out of one of the lines to eliminate the vapor lock.  Now I get no water at all although the tank is full.  Is there a tube or hose inside the tank that might have fallen in?  Is there a screen that could be plugged up?  My neighbor and I put a new pump onto the line that come from the tank, but nothing.  Any help on were to look for trouble shooting would be appreciated.

[Dr4Film]

My 60 gallon fresh water tank has a fitting near the base of the tank which is where the pump gets its water through. The RV water pumps are self-priming so as long as the PEX line from the tank to the pump has water in it then it should work.

I would check your inline filter making sure it is not plugged up. Disconnect the pump from the input side including the filter to see if water flows by itself. If not then your problem is in the line from the tank to the pump.

[Dennis H]

Does the pump turn on? In answer to your question, yes there is a screen/filter, but it's usually found on the pump itself. Did you turn off the water supply, i.e. winterizing valve, in order to change out the pump?? ..let us know....Dennis

[gpafox@att.net]

the pump does turn on.  I have disconnected both the hoses both sides of the pump.  I am getting no water from the tank at all.  If a line is plugged how would I free it up?
 

[Bob Nodine]

4 hours ago, gpafox@att.net said:

the pump does turn on.  I have disconnected both the hoses both sides of the pump.  I am getting no water from the tank at all.  If a line is plugged how would I free it up?
 

Disconnect the line from the pump. If water does not run out and the fresh water tank is full then you either have a plugged line or the vent for the tank is stopped up and the tank is air locked.  You can use compressed air to blow back up thru the line disconnected from the pump and attempt to clear the obstruction. I doubt the tank is air locked. There is an overflow somewhere on the tank. To test that it is clear simply fill the tank from the city water connection until the tank overflows.

Edited May 15, 2020 by Bob Nodine

[Dennis H]

6 hours ago, Bob Nodine said:

/snip/  You can use compressed air to blow back up thru the line disconnected from the pump and attempt to clear the obstruction.

Be very careful using compressed air. Too high a pressure and you may find water everywhere....I'm thinking a dauber nest perhaps in the overflow or a 'forgotten' / accidental shut off valve........Dennis

[96 EVO]

It's not gravity fed!

My fresh tank is in the first bay behind the front axle. The pex line goes from floor level, up to bay ceiling level, travels about a third of the length of the coach, then down to the water pump.

[Ivan K]

That is an unusual configuration since pumps are usually better at pushing than pulling. Can you siphon some water to get it flowing and then connect back to the pump inlet to get the pump primed? From that point it should work until the pump gets dry again.

Edited May 16, 2020 by Ivan K

[Dennis H]

Ok. Kinda hard to trouble shoot without actually seeing your setup, but here goes.  Your water tank fills either while hooked up to city water via knife valve or through the fill cup on the side of the coach.  On the tube from the fill cup there is another hose that allows air into the tank so it's gravity filled. Similarly when you use the knife valve as the water tank fills the air it's displacing escapes through this small hose. First thing to check is ensure this small hose is clear. It also doubles as an overflow so an easy check is to overfill the fresh water tank and see where the extra water comes out. If it comes back out the fill tube then the overflow is blocked and needs to be cleaned. Assuming that is successful, your next check should be your one way valves. You have one at the city water fill and another should be built into the pump itself although some coaches have an inline just before the pump. Check to see which you have. Now you said you've checked the pump.  I'm making zero assumptions here. Hook the pump up to a good 12VDC supply and attach a hose to the receiver end with the other end in a bucket. Turn it on and see if it pumps. You could have a bad check valve inside that pump even though it might be new. Finally, if all that works, reinstall the pump, turn it on, then open each faucet for about 30 seconds. This should prime the pump and purge any air out of the system. If none of this works, you'll have to check your system to see if there's another in line check valve somewhere in the system. If you have a winterizer system, you might find one there.....Dennis

[Bob Nodine]

13 hours ago, 96 EVO said:

It's not gravity fed!

My fresh tank is in the first bay behind the front axle. The pex line goes from floor level, up to bay ceiling level, travels about a third of the length of the coach, then down to the water pump.

That is just a plain crazy way to design the system. If it were my coach I would move the water pump to the bay were the tank is and get it as low a possible. Your pump may be having trouble getting primed that far from the tank with the non-gravity feed configuration. Any air in the line will make priming the pump difficult. Our original pump was down low in the bay an easily primed by gravity feed. That pump went south and I replaced it with a much better pump that had a good lifting spec because the pump had to be relocated to the ceiling of the compartment due it's increased size. It works now but I had a time getting all the air out and it primed the first time.

[96 EVO]

Bob, I've never had an issue priming the pump in the spring. Put some water in the tank, open a tap, turn on pump, and within 30-40 sec, it's running a solid stream.

[gpafox@att.net]

Well I would like to say thankyou for all your help. The overflow line was plugged up. I filled the tank all the way up twice and put a little air presure in the tank and whala every thing works.

[Dennis H]

6 hours ago, gpafox@att.net said:

Well I would like to say thankyou for all your help. The overflow line was plugged up. I filled the tank all the way up twice and put a little air presure in the tank and whala every thing works.

Thumbs up! Glad the 'fix' was cheap too....Dennis