Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses a water pump which cycles every few seconds, with no apparent cause.
Thanks for joining RV Travel – I’ve really enjoyed your columns. My question: We have a 2018 Thor Freedom Elite on a Ford E-350 chassis. It has a Shurflo 4008-101-A65 water pump rated at 3 gpm and 55 psi. The pump pumps fine with plenty of flow. The problem: When there is no demand for water, about every 10 – 15 seconds, the pump “burps” or cycles for about one second. I have found no leaks or evidence thereof and no faucets or the toilet are leaking.
While there is no problem with leaks or water delivery, it is kind of annoying. Any suggestions? Thanks. —Don
Thank you for the welcome. Your pump is an on-demand type pump and when the switch is on, it senses pressure in the outgoing line and stays put. When you open a faucet, the pressure drops in that line and turns the pump on.
The first thing I would do is remove the pump and bench test it to find out if the pump is not holding pressure. There is a check valve and diaphragm that can get clogged with sediment, rupture slightly, or it could have frozen in the winter.
Make sure you test the screen, as well, when you bench test it. If it still cycles, purchase a new diaphragm kit and replace it. These are very easy to rebuild. Some models have a pressure switch adjustment screw that can be adjusted with an allen wrench, so check for that and make sure all screws are tight.
If it does not cycle on the bench test, then there is a leak somewhere in the plumbing system. We had this exact situation with a 2003 Winnebago Brave and it was quite a search for the culprit. We started with the shower as it seemed to have a slight drip after turning off the shower. This could be a source as you would typically not look in the shower. When the switch was turned off, naturally it did not cycle, so the water could have dried up before looking in there. We put all new seats and parts in the faucets and that did not fix the problem.
Another area to look at is the toilet as water could trickle past the flush ball and ball seal if the water valve or pedal is leaking.
Ours turned out to be the city water to fresh water fill valve. When connected to city water, this model can fill the fresh water tank without removing the hose and using the gravity fill. Simply turn the switch lever to tank fill and it will fill it when the water supply is turned on. The issue we had was it would not seal tight when the switch was in the city water position, so I believe air would leak in and release pressure. We replaced the switch and it worked as designed. We got lucky, as the suggestion came from Owner Relations at Winnebago.
Read more from Dave here.
HAVE A QUESTION FOR DAVE?
We have started a new forum link for Ask Dave. Please be as brief as possible. Attach a photo or two if it might help Dave with his response.