Diagnosing a Pump That Cycles On and Off Every Few Seconds

Intermittent Pump Cycling – Pressure Switch or System Type?

A 10+ year old pump cycles on for ~10 seconds, off for ~5 minutes, repeatedly. The owner is unsure if a pressure switch exists.

Identify Your System Type

Look for a steel pressure tank near the pump. If present, the system uses a pressure switch (mounted on the tank plumbing) to control the pump. No tank means the pump is likely controlled by the irrigation controller via a pump start relay.

If Pressure Tank Exists

• Check the pressure switch settings (cut-in/cut-out). The differential may be too narrow, or the tank may be waterlogged (loss of air cushion).
• Drain the tank, recharge air to 2 psi below cut-in pressure, and adjust the switch if needed.

If No Tank (Irrigation Direct-Drive)

The cycling may be caused by a zone with too little flow demand, causing the pump to hit its high-pressure shutoff quickly. See the article on "Pump Quick Cycling on One Zone Only" for that scenario.

Confirm the presence of a pressure tank to determine the correct troubleshooting path.