pump lost its prime

[nayther]

strange thing happened this trip. Ran out of water while boondocking in Quartzsite on last day, conservation was not adequate. We were with some friends to stole some of their water (toy hauler with 150 gallons) using 1/2 gallon jugs to get by the last night/morning as we were headed to hookups in Tucson didn't bother to dump/fill there. At Tucson KOA dumped and filled water tank, ran pump and it pumped up just fine, probably still air in water heater but it pressurized it enough to cycle off so all was good. Headed back to Quartzsite on Sunday, stopped mid-trip to use the pot and were were on a bit of an uphill but with tank full should have had flooded pump suction but could't get water for flushing. Continued on and when all set up pump would not pump water, just ran and ran. Pump is in pass through behind divider so EVERYTHING in storage had to come out, thought might have sucked up debris and strainer was probably plugged. Strainer was perfectly clear. Disconnected pump discharge and DW hit the switch, nothing came out. Sucked on inlet pipe and water came up so knew it wasn't blocked. Reconnected inlet, held thumb over discharge and it started to pump, reconnected and all is fine.


These pumps are "self-priming" so should not have needed to go through this priming routine and have never had to on other campers.



Also there is no check valve on the pump discharge so what keeps the city water from backfeeding into the pump/tank?


Thoughts/suggestions?

[SeaDog]

the check valve is internal to the pump. you may just have had allot of air in the suction line.

[5picker]

The pumps are self priming but I've experienced more than once, if I didn't open a faucet and release the air on the pressure side, the pump wouldn't prime.

As SeaDog said... you may have just had a large amount of air and some of that was likely on both sides of the pump.

[nayther]

Originally Posted by 5picker

The pumps are self priming but I've experienced more than once, if I didn't open a faucet and release the air on the pressure side, the pump wouldn't prime.

As SeaDog said... you may have just had a large amount of air and some of that was likely on both sides of the pump.

I let it run for 10 minutes and it never sucked up any water. I've completely drained the system in my last rig and it primed right up. Self priming should not require any assistance.

[D W]

It sounds like the pump is in by-pass mode. Often times, after a CW connection, a residual pressure will be maintained in the line. The pump can not overcome this pressure and it goes into the by-pass mode. I've had this happen several times. Just opening a faucet didn't relieve it. My solution was to go to the CW connection, remove the screen and push the check valve button to release the residual pressure. The first time I got a bath! From then on I now stand off to the side.

After that the pump worked fine.

[Larry-NC]

Originally Posted by D W

It sounds like the pump is in by-pass mode. Often times, after a CW connection, a residual pressure will be maintained in the line. The pump can not overcome this pressure and it goes into the by-pass mode. I've had this happen several times. Just opening a faucet didn't relieve it. My solution was to go to the CW connection, remove the screen and push the check valve button to release the residual pressure. The first time I got a bath! From then on I now stand off to the side.

After that the pump worked fine.

I don't understand why opening a faucet wouldn't have relieved the pressure. Especially if the pump was off when you did it.

[D W]

Originally Posted by Larry-NC

I don't understand why opening a faucet wouldn't have relieved the pressure. Especially if the pump was off when you did it.

To be perfectly honest, I don't understand it either, but I've had it happen three times in a 4 year period. Every time, when I relieve the pressure at the CW check valve, the pump comes out of by-pass mode and starts pumping again.

[nayther]

Originally Posted by D W

To be perfectly honest, I don't understand it either, but I've had it happen three times in a 4 year period. Every time, when I relieve the pressure at the CW check valve, the pump comes out of by-pass mode and starts pumping again.

I'll take a look at that, I agree makes no sense but neither did what I experienced either, especially since I disconnected the discharge from the pump and there was no pressure in that line and it is directly connected to the city water connection.