When a self-priming pump suddenly stops delivering water, it can be surprisingly frustrating—especially if the pump has always worked fine before. The good news? Most “no-water” problems come from only a few common issues, and you can usually troubleshoot them without tearing the whole system apart.
If you're using a booster pump together with your self-priming pump, the steps below also apply—just note which part of the system you're testing.
1. First Things First: Check the Power & Pump Status
Sometimes the problem isn’t the pump—it’s the basics.
* Is the pump plugged in securely?
* Did the breaker trip?
* Is the pump humming but not running?
* Any unusual vibration or heat?
If the motor doesn’t start at all, you may be dealing with a capacitor failure, wiring issue, or motor damage.
2. Look for Air Leaks — The 1 Enemy of Self-Priming Pumps
A self-priming pump** must create a vacuum to lift water.
Any tiny air leak can break that vacuum and stop the pump from pulling water.
Common leak points:
* Loose inlet pipe connections
* Cracked or old PVC fittings
* Worn mechanical seal
* Loose drain screw
* Aging rubber gaskets
Tip: When the pump runs, listen closely—air leaks sometimes make a faint whistling or sucking sound.
3. Make Sure the Pump Casing Is Fully Primed
A self-priming pump cannot operate with an empty chamber.
You need to:
1. Open the priming port
2. Fill the pump completely with water
3. Tighten the cap again
4. Restart the pump
If the chamber isn’t full, the pump will simply spin without lifting anything.
4. Check the Inlet Pipe for Blockages
Leaves, sand, plastic bags, sludge—anything can block the flow.
Symptoms:
* Pump starts normally but no water comes out
* Suction pipe vibrates slightly
* Output pressure stays at zero
Remove the inlet pipe and inspect the strainer or foot valve. Blocked foot valves are extremely common on older installations.
5. Inspect the Foot Valve or Check Valve
If you’re using a booster pump and self-priming pump together, the check valve becomes even more important.
Problems to watch for:
* Foot valve stuck closed
* Spring broken
* Rubber flap hardened
* Valve full of debris
A damaged check valve lets water flow back into the tank or well, causing the pump to lose its prime every time you turn it off.
6. Is the Suction Lift Too High?
Every self-priming pump has a limit—usually 6–8 meters of suction lift.
If your installation is too deep:
* The pump will run
* But it will NEVER pull water
* Even if everything else is perfect
In that case, you may need a deep well pump, ejector pump, or a booster pump.
7. Internal Pump Blockages or Impeller Damage
Inside the pump, the impeller may be:
* Worn down
* Jammed by debris
* Broken
* Rusted or corroded
If the pump feels unusually noisy or grinding,shut it down immediately and inspect internally.
