Pool Pumps - Will Not Prime

The Pump Will Not Prime

A "primed" pump is one which has a solid flow of water going through it.  When a pump is not primed, the motor is running, but no water is being pumped through it.  If a pump runs unprimed for a length of time, it can do serious damage to the pump components.

It is normal for a pump to take up to a minute or two to prime up.  In some extreme cases, it might take up to five minutes to prime a pump.  If it does not prime up within that time, then something is probably wrong.  

When attempting to prime a pump, make sure that the pump pot is full of water and that the lid is securely attached.  Make sure also that the lid o-ring is sealing properly.  A light coat of silicone lube is a good idea.  If the lid o-ring is hard, flat or damaged, it should be replaced.

If the pump shows no signs of priming up on its own, it may be necessary to force water from the skimmer into the pump to encourage the pump to prime.  This is sometimes needed if the pump is situated more than a foot above the water level.  

The best way to do this is by using a "drain jet" in the skimmer.  The diagram shows how it is done.

1.  Hook the drain jet up to a garden hose and insert it into the skimmer line that leads to the pump.  Shut off or plug all the other intakes (main drains, skimmers).  This will force water into the pump.

2.  Turn on the water and let it force water up into the pump trap.  When the water has filled the trap, turn the pump on.

3.  As the pump starts to prime, open up one of the other intakes partially in order to keep from starving the pump.  This will allow the pump to fully prime.  As the pump primes, open the other intakes gradually, allowing the pump to pull out any trapped air.  

4.  When the pump is fully primed, turn off the drain jet and remove it.  Be careful that you do not allow the drain jet to be sucked into the skimmer line.  

If the pump will not prime, even using a drain jet, then check the pump components for blockage or breakage.

If the pump primes, but then will not stay primed after the drain jet is removed, then check for air leaks in the system.

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