[Twins]

My water pump cycles for about a second every 30 or 40 minutes... I am not finding any water inside the coach or outside... is this normal???

[NewellCrazy]

Is there a check valve on the pump output side?

[77newell]

The pressure sensor, probably in the pump itself based on the vintage of your coach, is detecting low pressure and turning the pump on. If there are no external leaks then I would think the one-way valves in the pump are leaking. The pump in my 77 coach required the valve replacement kit to solve this same symptom. You can even buy a whole new pump head if the motor is fine.

[prairieschooner]

Yes, it could be the pump and there is an easy way to check. Bypass the Plumbing and just run a short length of hose direct from the pump and plug it. If the Pump sill Cycles then it is at fault, Hopefully it is a SHURFLO because they are very reliable and Parts are readily available, if not then these are around $100.00 or so (AMAZON).
Now if the problem is in the plumbing use some Food Coloring, I suggest Red or Blue NOT YELLOW! for obvious reasons. You would be surprised how easy this makes finding a leak.
Good Luck!

[Chester B. Stone, Jr.]

An air pocket in the system can cause this if the check valve is OK.

[Newell Attack]

I had this happen about a year ago. Drove me crazy! Finally changed out the water pump and that fixed the problem. I surmised that it was the internal check valve in the pump that was allowing the pressure to bleed back into the water tank.

[Newell Boss]

Does your coach have an accumulator tank in the water system? If so, it may have lost the air in the bladder causing the pump to be more sensitive to pressure changes.