Pool Pump Won't Prime? Here's What You Need to do

If your pump will not prime follow this checklist to eliminate the potential causes one by one. While this list of possible causes is fairly comprehensive it is not exhaustive and there are a few rare circumstances that exist which a typical homeowner will not be able to diagnose such as a break or leak in an underground line.

(Remember, just because you may be able to get the pump running does not mean that the pump, plumbing, or electrical equipment is working correctly.)

1. Make sure the water level in the pool is high enough so it can flow into the skimmers.
2. Make sure the skimmer doors (also called weirs) are not stuck or hung up. This will obstruct the flow to the skimmers. (These first 2 steps account for 90 percent of pumps that won’t prime.) Occasionally skimmer doors or weirs hang up due to waves or they can hang up if the filter were to have air trapped in the top of the tank that decompresses when cycled off causing water to rush backwards through the lines.
3. Make sure the valve handles are screwed on tightly. If you have a Jandy or Compool valve with a small threaded tab at the top be careful not to over tighten the tab as they are prone to breaking easily.
4. When you turn on the pump does it just hum? If so there may be electrical problems. You should call a pool professional to test the voltage on the pump, ensure the shaft is free, and potentially test the capacitor(s) to diagnose the problem unless you are familiar with these inner workings of a motor and are willing to undertake disassembling the pump and resealing it.
5. If you have an Intermatic timer mechanism, can you see the gears turning? The most common and oldest style of Intermatic timer is commonly referred to as a yellow dial timer. On those types of timers if the dial pointer is directly over the “off” lug it can prevent the tab hanging down from fully moving to the Right when a user attempts to turn on the timer manually for the pump to run.
6. If you have an Aqualink or Aqualink RS control center (as well as some Gold Line and Compool varieties) listen when you push the button to power on the pump… do you hear a click? If not you may have a damaged power board or relay out on the control center. Is there power at the equipment when you turn on the other equipment? Sometimes a breaker or GFCI has popped. Sometimes a main power switch (often looking like a light switch) has been turned off.
7. Check the pump lid and pump lid o-ring and make sure they do not have any cracks from age. Lubricate the pump lid o-ring and ensure it is clean.
8. Make sure there are no cracks, chips, or breaks in the pump basket. If it is a Pentair (previously Pac-Fab) Challenger pump, and it has a factory pump basket with a black handle, make sure the handle is on the attached to the basket . The black handle needs to be snapped onto the basket on both sides so it does not move up and down. Make sure that the basket is lined up with the internal grove and seated fully down into the pump basket pot area.
9. Fill the pot with water, screw on the lid and turn on the pump.
10. Open the filter air relief valve while the pump is trying to prime.
11. If you have a SPA you can adjust the water flow to suck from the SPA drain. (Make sure to change the valve back to the correct position once you are finished either attempting or priming the pump. This can be very helpful if the spa and or the equipment is elevated above the pool water level.)
12. If the pump is still not priming see if you can see any leaks around the pump and plumbing. Is the plumbing going into or out of the pump loose? If the suction side connection is loose this will cause the pump to suck air when attempting to prime and either significantly impair it from fully priming or prevent it from priming at all.
13. Repeat step 10 and turn on the pump again but this time make sure you have a running garden hose present beforehand. Run the garden hose water over the suction side connection on the pump pot and see if you can improve the water flow into the pump. Also try running the garden hose over any open suction side valves to see if you can discover that they are sucking in air. If the pump sucks in more water (meaning the garden hose significantly improves the priming capacity) then you have probably discovered a suction side leak that is preventing the pump from fully priming or priming at all.

These steps will resolve by far most pump priming issues. If these steps do not yield success then call a pool professional for a diagnosis of your system.

Best wishes with successfully priming your pump!