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Fix a pump that will not prime

We'll check the suction line, foot valve, and priming—then fix or replace—or tell you when to call a pro.

Troubleshooting · Home maintenance
20–45 min
What you'll need
  • Water (for priming)
  • Wrenches and screwdrivers
  • Replacement foot valve (if needed)
Step 1 of 6

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Steps

Goal: Confirm the symptom, then check for leaks and prime the pump.

  • Start the pump. The pump runs but no water flows from the discharge.
  • Good: Pump runs but no water—prime fault. Proceed to Check for leaks.
  • Bad: Pump does not run—different problem (power, pressure switch).

Check for leaks

Goal: Rule out air leaks in the suction line.

  • Inspect all connections on the suction line. Tighten loose fittings. Check for cracks.
  • Good: Leak found and fixed. Proceed to Prime the pump.
  • Bad: No obvious leak—check the foot valve.

Prime the pump

Goal: Fill the pump and suction line with water so the pump can prime.

  • Remove the priming plug. Pour water until the pump and line are full. Replace the plug. Start the pump.
  • Good: Water flows. Pump is primed.
  • Bad: Still no water—check lift or call a pro.

When to get help

Call a well or pump professional if:

  • The pump is in a well.
  • The suction line is long or buried.
  • You cannot find the leak.
  • You are not comfortable with plumbing.

Verification

  • Water flows from the discharge when the pump runs.
  • No air bubbles in the suction line.
  • Pump holds prime when stopped (foot valve holds).

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the pump runs but no water flows.
  2. Check for leaks Inspect suction line and fittings for air leaks.
  3. Prime and check foot valve Prime the pump; replace foot valve if faulty.
  4. Check impeller Inspect impeller if leaks are ruled out.
  5. Call a pro Well pump, long suction line, or impeller work—call a professional.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Pump type and location
  • Suction line length and condition
  • Steps already tried

Does the pump run but not move water?

Pump runs, discharge is dry. That is a failure to prime.

Start the pump. Good: pump runs but no water—prime fault. Bad: pump does not run—different problem (power, pressure switch).

Yes No

You can change your answer later.

Are there air leaks in the suction line?

Air leaks prevent priming. Check all fittings.

Inspect the suction line and fittings. Tighten loose connections. Good: leak found and fixed. Bad: no obvious leak—check foot valve.

Yes (found) No

You can change your answer later.

Is the foot valve faulty?

A faulty foot valve lets water drain and air in.

If you can access the foot valve, replace it. If it is in a well or buried, call a pro. Good: foot valve replaced; prime the pump. Bad: foot valve not accessible—call a pro.

Yes No

You can change your answer later.

Prime the pump

Fill the pump and suction line with water. Remove the priming plug, pour water in, replace the plug. Start the pump. Good: water flows. Bad: still no water—check lift or call a pro.

Yes No

You can change your answer later.

Pump primed

The pump should now move water. Confirm flow at the discharge.

Done

Call a pro

Call a well or pump professional if the pump is in a well, the suction line is long or buried, or you cannot find the leak.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a pump not prime?
Common causes: air leak in the suction line, faulty or stuck foot valve, pump or suction line not filled with water, or the pump is above the water source and cannot pull water up. Check for leaks and prime the pump.
Can I fix a pump that will not prime myself?
Yes, for above-ground pumps. You can check for leaks, prime the pump, and replace the foot valve. Well pumps and submersibles may need a professional.
When should I call a pro for a pump that will not prime?
Call a well or pump professional if the pump is in a well, the suction line is long or buried, you cannot find the leak, or you are not comfortable with plumbing.

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