Green Guru LLC Irrigation & Landscape Lighting

Pump Intake Diagnostics

Lake Pump Foot Valve

Foot-valve issues are a leading cause of lost prime on lake and river systems. Intake diagnostics prevent unnecessary pump replacement.

This guide isolates source-side prime failures so repairs target the actual intake issue.

Prime-loss diagnostics Intake leakback checks Startup reliability Service-scoped repair

Quick Answer: Is the pump bad if prime keeps dropping?

Not always. Intake-side foot-valve and suction-path issues frequently cause prime loss even with a serviceable pump.

Pump Replacement Guessing vs. Intake-First Diagnostics

Pump-First Guessing Foot-Valve Diagnostics
Assume motor/pump failure firstVerify intake and foot-valve retention first
Higher replacement-cost riskTargeted intake repair where confirmed
Prime loss may continuePrime hold verified after correction
Limited pattern documentationStartup/hold behavior documented

When this is likely your issue

  • Pump requires repeated priming.
  • Startup is delayed after idle windows.
  • Pressure drops back after shutdown.
  • Flow weakens quickly during runs.

What we check before replacement

  • Prime retention between cycles.
  • Intake and suction-side leak indicators.
  • Debris restriction at intake path.
  • Startup stability after corrective scope.

Deployment workflow

  • 1

    Capture prime-loss pattern

    Document when prime drops and how startup lag appears across cycles.

  • 2

    Inspect intake path and foot valve

    Check suction-side components for leakback or restriction before pump replacement.

  • 3

    Apply targeted intake repair

    Repair or replace foot-valve path where diagnostics confirm source-side failure.

  • 4

    Validate repeat startup behavior

    Confirm stable prime and predictable startup in repeated tests.

Related guides

FAQs

What does a pump foot valve do?

It helps retain prime and limit backflow loss at the intake when the pump is off.

Can a bad foot valve mimic pump failure?

Yes. Prime loss and delayed startup can look like pump failure when intake retention is the issue.

Why does prime drop after shutdown?

Leakback through intake-side components is a common cause.

Should check valves also be inspected?

Yes. Foot and check valve behavior are evaluated together during diagnostics.

Can intake debris cause similar symptoms?

Yes. Restriction can reduce flow and destabilize startup behavior.

Do you replace pumps immediately for prime issues?

No. Intake and control-side causes are isolated first.

Is this common during seasonal startup?

Yes. Prime-retention issues often surface at spring startup.

Is this a direct parts-fit guarantee page?

No. It is a service-first diagnostic reference with on-site scope confirmation.

At a glance

Foot valve diagnostics facts
IndustryPump-fed irrigation
ComponentIntake-side foot valve
Primary symptomPrime loss / delayed startup
Key checksPrime hold, leakback, intake restriction, startup consistency
Service noteIntake diagnosis precedes major replacement recommendations

Need it diagnosed?

We isolate intake-side prime failures before recommending high-cost pump replacement scope.

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Related: Pump systems hub