Water pump won't stay primed

[bitNine]

Hi everyone, my trailer is a almost 5 years old. Just pulled it out two weeks ago for our earliest camping trip ever. Last weekend right before we left, I waited until the last moment to prime the water pump, because it's still pretty cold here. Once I got it going, everything seemed ok, but it didn't sound normal. It takes longer to recover each time it's used. It seemed ok otherwise. Well, first time we went to use it when we arrived at our destination, it wasn't primed. That's not normal. It gets primed, and stays pressurized. It's not leaking on the pressurized side, because I don't hear it running when water isn't used. But after 30 minutes of no water use, it starts to lose its prime, and it takes a good 15 seconds to recover. First thing in the morning takes even longer.

I've looked at connections, removed strainer and checked. Everything is tight. Checked the bypass valve, too. Water flows great once it's primed, but the pump just won't stay primed. Is this the pump going bad?

[bitNine]

I may have solved my own problem. Being the tinkerer I am, I just took the pump head apart. I didn't really see anything wrong, so I cleaned it up. Especially an o-ring up top that looked a tad gunky. Once I got it hooked back up, it sounds like a new pump. Hoping it fixes the prime loss, too.

[bitNine]

I spoke too soon. I let it sit all night, came back out and while there was still lots of pressure, it took a good 15 seconds for the pump to prime again. Not sure what to do about that. Pump certainly sounds better and pressurizes faster though.

[SeaDog]

when you say prime you are you meaning come up to pressure and shut off? If it wasn't priming you would have no water pressure. Its not unusual for a pump to loose a little pressure while sitting because of the internal check valve leaking back. As long as its not cycling on and off. A five year old pump may have to run a little longer then when new.

[marinerjoe]

Sounds like it's time to look at the suction side of your setup, starting with the pump itself, and working towards the water tank. Including the diverter valve that allows you to choose between the winterizing connection or the storage tank itself.. Make sure all the connections are tight. Other than that, not sure what else you can do.

[bitNine]

Originally Posted by SeaDog

when you say prime you are you meaning come up to pressure and shut off? If it wasn't priming you would have no water pressure. Its not unusual for a pump to loose a little pressure while sitting because of the internal check valve leaking back. As long as its not cycling on and off. A five year old pump may have to run a little longer then when new.

No, the inlet side is allowing water to drop back into the tank, so after sitting for awhile it takes the pump 15 seconds or so to get pressure to build properly. It's as if I went to the pump, disconnected the inlet line, let the water flow back to the tank, reconnected and turned on the pump. Takes 15 seconds or so to pick up from the fresh tank again.

[HangDiver]

Apparently the check valve on the pump is not seating properly.

[bitNine]

Originally Posted by marinerjoe

Sounds like it's time to look at the suction side of your setup, starting with the pump itself, and working towards the water tank. Including the diverter valve that allows you to choose between the winterizing connection or the storage tank itself.. Make sure all the connections are tight. Other than that, not sure what else you can do.

Thankfully mine is SUPER simple. The tank inlet, vent tube, and tube going to the pump are all right next to the water pump where it goes into the tank. So the pickup line is only about 18" long above the floor, and does straight down into the tank. It comes out of the tank, goes into the diverter valve, then from there it's about 3" of hose to the elbow right before it goes into the pump. So there's 3 crimp connectors there. Then on the T side of the diverter is about an 18" section of hose with a cap on the end for winterizing. Honestly not sure where it could be sucking any air from. I guess I could go back and re-crimp all those connectors, or maybe swap them out for screw-type hose clamps.

[marinerjoe]

Originally Posted by HangDiver

Apparently the check valve on the pump is not seating properly.

That may not be the case if he's getting a decent shot of water, and then it drops off until the prime builds back up again.

[Flybob]

Recheck the winterizing valve. Even a small leak will allow air to enter and the prime will be lost.

[bitNine]

Originally Posted by marinerjoe

That may not be the case if he's getting a decent shot of water, and then it drops off until the prime builds back up again.

That is EXACTLY what is happening. Pressure bursts out, drops, then 15 seconds to build again, back to normal.

[bitNine]

Originally Posted by Flybob

Recheck the winterizing valve. Even a small leak will allow air to enter and the prime will be lost.

Will do. Maybe I'll just pull the valve off completely and try to get rid of as many connectors as possible in order to test.

[chaps2018]

Just checking to confirm no air in the system. My pump acts squirrelly when I don't burp the air from the unused washers/dryer lines after winterizing.

[MacDR]

My Divertor Valve had a crack in it by the threads ..I just by passed it and my pump works great. I didn't replace the valve.

[Murbella7]

Originally Posted by marinerjoe

That may not be the case if he's getting a decent shot of water, and then it drops off until the prime builds back up again.

That shot of water is only what is in the outlet pipes, sitting there after the pump stops. If the check valve is faulty, the pump will not retain the prime.

[Dwilcox]

If he has the pre filter on the inlet side of pump, if leaking a little it would allow the water to drain back to tank. Check cup for crack and o-ring for damage.

[bitNine]

Thanks for the input everyone. I focused on the crimp connections on the inlet side and re-crimped them all. After 4 hours there was still prime, so I think I got it! If it happens again I will probably replace those crimp rings with something else.