Water pump mystery

[handlebarjim]

Shurflo pump

Had rig 10 years, after last water fill, pump began to cycle (approx 20 sec) , more troubling is every cycle produces a momentary power interruption in 12 volt. Never had problem before. Searched extensively for leak. None found. Installed my spare pump, same result.

Pump is normally on 24/7. Even when hooked-up I use pump & tank. Power interruption is impossible to not have noticed previously !

                                      Thanks, Handlebarjim

[Carolaow]

Do you happen to have a four-way water input valve (the kind that you can switch between using city water, using the tank, filling the tank, or winterizing)?  The one used by my rig's manufacturer has been causing a lot of problems for customers lately.  It can cause cycling of the water pump as you describe, as well as other problems.  Sorry I don't know the brand name of the valve, but I suppose any of them could go bad.  Mine got so bad that the pump cycled every couple of minutes or so and if I turned the pump off so that I didn't have to listen to it, when I turned it on to use the water, it cycled a full half minute or more to get water back into all the pipes.  You could hear the water flowing near each faucet.  Anyways, just a thought.

[Alie&Jim's Carrilite]

2 hours ago, handlebarjim said:

Shurflo pump

Had rig 10 years, after last water fill, pump began to cycle (approx 20 sec) , more troubling is every cycle produces a momentary power interruption in 12 volt. Never had problem before. Searched extensively for leak. None found. Installed my spare pump, same result.

Pump is normally on 24/7. Even when hooked-up I use pump & tank. Power interruption is impossible to not have noticed previously !

                                      Thanks, Handlebarjim

Check your wiring for the new pump.  Follow the wiring as far as you can, and check the connections behind the fuse panel.  A loose ground or other connection would cause the interruption.  As for the pump wanting to cycle itself,  is there a check valve between the tank and pump that could be leaking back into the tank?

[RV_]

OK,

This will sound dumb but if you have an outside shower check to see that the valves for hot and cold are turned off. I turned mine off at the shower head and although it never leaked the hot and cold sides were mixing and flowing around the head with demand from other outputs.

You need to check your 12 volt fuse for that circuit and be sure it is the right amperage.

[Kirk W]

4 hours ago, handlebarjim said:

Had rig 10 years, after last water fill, pump began to cycle (approx 20 sec) , more troubling is every cycle produces a momentary power interruption in 12 volt. Never had problem before. Searched extensively for leak. None found. Installed my spare pump, same result.

If you have a fill valve from your city water connection, check it to be sure that it is closed completely as it could possibly leak to cause a loss of pressure, as it is pressure in the lines that cause the pump to turn off. That would not explain an interruption of the 12V power. Am I correct to assume that your lights go off or something else is indicating the loss of 12V? Might the pump be cycling not because it is turning off but rather due to the loss of 12V that you are reporting?

[Smitty77_7]

Electrical is one issue, and follow the advise given.

Pump cycling is a second issue, and if no signs of leaking anywhere, agree good chance it's a back pressure check valve allowing back flow into the water tank. 

Good luck!!! And please post back what you find out, as it could help other's researching problems in the future.

Smitty