Irrigation Pump Loses Prime: Suction Line Air Leak Detection

Pump Primes But Won't Hold Prime: Tiny Air Leak on Suction Side

Cottage on Muskegon River. Pump primes, runs, then loses prime after shutdown. Check valve installed but problem persists.

Root Cause

Microscopic air leak in suction piping between pump and river. Even a pinhole lets air in, breaking the siphon.

Test Method

1. Connect a garden hose from house pressure to the pump suction (via a hose bib adapter). 2. Pressurize the suction line (20–30 PSI). 3. Spray soapy water on every joint, fitting, check valve, and foot valve. 4. Bubbles = air leak (which is a water leak under pressure).

Common Leak Points

• Check valve seat (debris prevents seal).
• Foot valve screen gasket.
• PVC glue joints (incomplete cure).
• Threaded adapters (need Teflon tape + paste).

Fix

Disassemble, clean, reassemble with fresh primer/cement or thread sealant. Re-test with hose pressure.