Fresh Water pump cycles on, off, on ,off..........

[340DA]

Another Season, New set of problems.....

When I turn on the breaker for the water pump, the fresh water pump that pumps the fresh water to the galley, head and cockpit sinks will quickly build pressure, then after that, it will cycle on for 1 second, off for 5 seconds, and repeat and repeat, this cycle on for 1 , off for 5 . It will continue this pattern until i turn off the circuit breaker.

I turned on all the faucets and there does not seem to be any air in the system. I cleaned out the clear plastic bowl that sits below the pump and that captures gunk. The pump itself works fine when and I turn on the faucets, pressure is fine and the pump pushes water fine.

Last year I replaced the fitting/tube that screws into the top of the fresh water holding tank because it had a cracked fitting on top of the tank. After that repair last year, the pump worked fine. I did NOT have this "cycling" issue last year. The pump itself was replaced in 2017

Any suggestions/recommendations as to why the cycling is occurring and how to resolve it?

 

[Halfhitch]

I see you hail from Long Island Sound. It gets cold up there. Is there any chance that water was left in the lines somewhere and it froze and split a fitting. Leaking down the pressure is most commonly caused by a leak. The fact that the pump was changed in 2017 makes me doubt the pump is bad.

Remove the discharge line at the pump. Screw on a blank fitting. A plug in other words and run the pump. It should run up to pressure and hold it. If it cycles the same as it does now then there is probably a pinhole in one of the rubber diaphragms. Look at the parts breakdown of your pump. Most diaphragm pumps have a replaceable diaphragm. Some are 3 pistons, some 4. Mr Google knows all about them.

 

[Blueone]

Another Season, New set of problems.....

When I turn on the breaker for the water pump, the fresh water pump that pumps the fresh water to the galley, head and cockpit sinks will quickly build pressure, then after that, it will cycle on for 1 second, off for 5 seconds, and repeat and repeat, this cycle on for 1 , off for 5 . It will continue this pattern until i turn off the circuit breaker.

I turned on all the faucets and there does not seem to be any air in the system. I cleaned out the clear plastic bowl that sits below the pump and that captures gunk. The pump itself works fine when and I turn on the faucets, pressure is fine and the pump pushes water fine.

Last year I replaced the fitting/tube that screws into the top of the fresh water holding tank because it had a cracked fitting on top of the tank. After that repair last year, the pump worked fine. I did NOT have this "cycling" issue last year. The pump itself was replaced in 2017

Any suggestions/recommendations as to why the cycling is occurring and how to resolve it?

Pressure switch….. common problem. They make a rebuild kit

 

[Carpediem44DB]

Rebuild or just clean out the diaphragms on the pump head or just replace it. Most folks find that the shur flo pumps only last about five years with out some sort of intervention. It is possible that you have a leak somewhere but more likely that the pump is just leaking down. I just replaced mine on recommendation of a site member. Great price point, has plenty of out put for my 506 water system and it is much quieter as well.
Amazon.com: DC HOUSE 42-Series Upgrade Water Diaphragm Pressure Pump, 5.0 GPM 55 PSI 12V DC Self Priming Water Pump for RV Caravan Marine Yacht : Patio, Lawn & Garden
Hope this helps

 

[Fill Ess]

There are so many connections that it could be a leak at any point in the system. Last time this happened to me, there was a leak at the dock water inlet in the transom. I just went around looking at each line until I found it.