Cycling Water pump with no water leaks

[TheProfessor]

Hey Gang-

A new issue has evolved. I have a water pump which has started to cycle in very short bursts (about a second) about once every five minutes. This would seem to indicate a low flow leak somewhere. Try as I might I can not find it anywhere!!

I am beginning to suspect a pressure switch problem but I haven't gotten into the pump yet.

After I put in a new water heater, I pressure tested with air at 30 psi (as per the water heater installation instructions) and checked everything with soapy water, like a propane system bubble test. All systems looked great... but

The bloody pump cycles! any suggestions???

Thanks in Advance
The Professor--

[HowieE]

The first thing I would do is disconnect the output of the pump and attach a length of say garden hose, with a means of shutting it off at the end of the hose, to the pump. Start the pump till the hose if full of water and the close off the hose. The pump should stop against the pressure switch. Let it sit. If there is no leak from the hose and the pump cycles the pump diaphragms are leaking back. You may have deposited dirt on the seats of one of the diaphragms when you did the air test. If so remove the top of the pump and clean the seats and diaphragms and retest.

If the pump holds with the hose full you may have a leak back in the trailer water system.

[RickDavis]

The shurflo pumps have a built in check valve. Occasionally something gets in it and the pump will appear to cycle for no reason. Sometimes this will clear up on its own. There is a rebuild kit available from shurflo

[Mike Leary]

There is a screw adjustment for the pump in the the front center to prevent it from cycling.

[Bluto]

On my old trailer, when my pump started that I took out the water saver disc out of the kitchen faucet. No more problem.

Thanks Mike Leary, I didn't know that. I'll have to file that bit of info away for some other time.