My water pump, which seems to work great as far as pressure and volume, every few seconds, maybe every five or so, slightly pulses. You hear a slight thump and the lights flicker just a slight bit. I’ve definitely determined it’s the pump. Turn it off, and the thumping quits. It seems the pressure drops just a little, just enough to kick on the pump which immediately applies enough pressure to shut it off again. I am virtually positive I have no leaks, which would have explained the problem. There’s no sign of a leak anywhere. So I’m wondering (first, do any of my thoughts thus far seem right) is there possibly a check valve that would allow water to flow back into my freshwater tank, just a little, just enough to relieve a little pressure in the pipes and therefore momentarily turn on the pump. It only turns on for a fraction of a second. It really sounds just like a bump. If so, is the check valve in the pump. It’s one of those SHURflo Revolution pumps that I put in five or six years ago to replace the OEM 4004 pump. It’s just started this recently.

Yes, as I read your post, I was thinking along those lines. Is it possible that the pump is leaking within itself? Relaxing the pressure?I have a boat, different water pump, but I have seen them leak inside themselves from years of wear. Then they dont pump or move water as efficiently.gh

If you have no leaks, then it's probably the check valves in the pump leaking down. They make rebuild kits for most pumps which usually come with a new diaphragm and new valves. Look online with your pump part number

Good chance it's backflow in the pump but do a good check of the plumbing. It could be a really slow leak and if left to continue could do a lot of damage before you find it.

rbcamping wrote:If you have no leaks, then it's probably the check valves in the pump leaking down. They make rebuild kits for most pumps which usually come with a new diaphragm and new valves. Look online with your pump part number^^^^ YES!

I will indeed verify that there are no plumbing leaks, but I’m almost positive there are none. I’m then going to find the check valve that could be offending (there could be more than one check valve, and, if so, I’ll replace them all). Though I’d forgotten till now, I remember quite a few years back I had a situation where my fresh water tank was mysteriously filling while on city water, and it was a check valve. Maybe the one I put in is slowly leaking. Or it could be the pump diaphragm. At least I feel I’m on the right track and will start searching down the culprit.

Water pump on fiver periodically pulses | Good Sam Community

groundhogy
Explorer
Sep 24, 2018
Yes, as I read your post, I was thinking along those lines.
Is it possible that the pump is leaking within itself? Relaxing the pressure?

I have a boat, different water pump, but I have seen them leak inside themselves from years of wear. Then they dont pump or move water as efficiently.
gh
rbcamping
Explorer
Sep 24, 2018
If you have no leaks, then it's probably the check valves in the pump leaking down. They make rebuild kits for most pumps which usually come with a new diaphragm and new valves. Look online with your pump part number
valhalla360
Navigator
Sep 24, 2018
Good chance it's backflow in the pump but do a good check of the plumbing. It could be a really slow leak and if left to continue could do a lot of damage before you find it.
mhardin
Explorer
Sep 24, 2018
rbcamping wrote:
If you have no leaks, then it's probably the check valves in the pump leaking down. They make rebuild kits for most pumps which usually come with a new diaphragm and new valves. Look online with your pump part number

^^^^ YES!
howardwheeler
Explorer
Sep 24, 2018
I will indeed verify that there are no plumbing leaks, but I’m almost positive there are none. I’m then going to find the check valve that could be offending (there could be more than one check valve, and, if so, I’ll replace them all). Though I’d forgotten till now, I remember quite a few years back I had a situation where my fresh water tank was mysteriously filling while on city water, and it was a check valve. Maybe the one I put in is slowly leaking. Or it could be the pump diaphragm. At least I feel I’m on the right track and will start searching down the culprit.
laknox
Nomad
Sep 24, 2018
Could also just be some schmutz in the check valve seat, keeping it from closing all the way.

Lyle
Bipeflier
Explorer
Sep 24, 2018
Also check the water heater drain and pop off.
ksg5000
Explorer
Sep 24, 2018
If you have outside shower make sure you include that in your search for "water leaks" - easy to overlook but they tend to have issues.
DutchmenSport
Explorer
Sep 24, 2018
Had a similar problem a couple years ago, but the pulsating became more and more increased. Eventually, I decided to buy a new pump after LOTS and LOTS of exploring searching for leaks.

After I pulled the old pump, I found the problem. It had 3 screws completely missing that held the impeller assembly in place. I found 2 of the missing screws and figure the 3rd fell into the underbelly and I'd never find it. So I installed a new pump and never had the problem again.

Check the screws on the pump itself. Make sure they are all tight and not sucking or allowing the seal to be broken, causing the water to back feel into the tank.

And just an FYI, it only did the pulsating when the water heater was on. When the water heater was cold, the pump never did the pulsing.
memtb
Explorer
Sep 26, 2018
We had something similar once, the city water connection check valve had some leak by.....took a while to find it!