Pump Pressure Switch Failure: Why Tapping Works Temporarily

Diagnosing a Faulty Pump Pressure Switch

If your sprinkler pump only starts when you physically tap the pressure switch enclosure, the switch contacts are likely pitted, corroded, or welded shut—common in older electromechanical switches.

Why Sanding Doesn't Last

Lightly sanding the contacts may restore conductivity briefly, but the underlying pitting and material loss cause rapid re-failure. The switch's snap-action mechanism also fatigues over time.

Correct Fix: Replace the Switch

1. Note the cut-in/cut-out pressures printed on the label inside the cover (e.g., 30/50 psi or 40/60 psi).
2. Purchase an exact-match replacement (same pressure range, same connection size).
3. Turn off power, drain system pressure, swap the switch, and re-pressurize.

Safety Note

Pressure switches control 120/240 VAC circuits. If you're uncomfortable working with electrical components, hire a licensed electrician or irrigation pro.