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If a Grundfos CR pump runs but gives no water after service, stop it. Confirm inlet supply, fill and vent it by the exact model manual, then check valves, inlet leaks and rotation. Never run it dry while testing.
Why can a running CR pump deliver no water?
Air is one cause, not a diagnosis. A blocked inlet, closed non-return valve, suction leak or reversed motor can look similar. Record inlet and outlet pressure, tank level and recent service changes. Use the instructions for the installed CR, CRI or CRN variant.
Use the symptom to choose the next check
Swipe the table horizontally to view all columns.
| Observation | Likely check | Next action |
|---|---|---|
| No liquid at inlet | Tank level, supply valve and inlet pressure | Restore inlet supply before restarting. |
| Flow returns after venting, then fails again | Incomplete filling or an inlet air leak | Vent by the manual; inspect inlet joints if air returns. |
| Inlet supplied, still no delivery | Blocked inlet, foot valve or non-return valve | Isolate and inspect the line and valve. |
Safe restart checklist
- Stop, lock out power and depressurize before opening a plug. Follow site rules and the exact Grundfos manual.
- Check tank level, inlet pressure, open valves, tight inlet joints and a clear strainer.
- Fill and vent at the specified points and in the specified sequence. Never open a pressurized plug.
- Have a qualified electrician verify rotation if wiring changed. Restart and watch pressure, flow, noise and leakage; stop if delivery is absent.
What should a parts or pump RFQ include?
Send the full nameplate code and serial number, liquid and temperature, pressure readings, valve layout, photos and service history. Confirm any damaged part by inspection. Price depends on the verified configuration and repair scope; request a matched quote.
Frequently asked questions
Is a CR pump self-priming?
Do not assume so. Follow the filling and venting instructions for the exact installed variant.
Should I replace the pump when the motor runs but no water comes out?
Not from that symptom alone. Check supply, air, valves, inlet leaks and rotation first. A confirmed internal fault may need parts or a replacement pump.
Grundfos product catalog · CR versus CRE selection guide · Request a pump or parts quote