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Thread: Pump and Plumbing Diagnostics

  1. Back To Top    #1

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    Pump and Plumbing Diagnostics

    My pump suddenly stopping pumping over night. The pump will not prime. Since then I have rebuilt the pump with a go kit which did not help.

    Problem:
    1. Occasional air bubbles coming out of returns. Overnight this because no flow out of returns.
    2. If I put my hand in the skimmer all the way down to the bottom I cannot feel a suction.


    Things I have tired:
    1. Rebuilt pump with go kit- did not help
    2. Drain king from the skimmer side- just a trickle of water coming out at the pump
    3. Plumbed the pump suction into a large bucket full of water and opened the pump discharge so that I could see the flow.- Lots of water flowing from the pump
    4. Connected the suction plumbing back up and watched the flow from the pump.- Barely anything coming out of the discharge
    5. Connected a 6.5hp shop vac to the suction line and blow through back into the skimmer.- It takes a minute or so but I end up with lots of bubbles. It looks like a hot tub in the skimmer. No debris coming out though. I did this once before rebuilding the pump with the same result.
    6. I have run water over the pump filter and connections with the pump running to check for air leaks. -No change in pump performance.

    Please help. Not sure what else to check here. I appreciate it
    13,500 gallon IG fiberglass, 3/4hp pump, sand filter

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    JasonLion's Avatar
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    Re: Pump and Plumbing Diagnostics

    There are two likely possibilities, either there is a fairly complete blockage of the plumbing on the pressure side of the pump, or there is a suction side air leak. I am inclined to suspect a pressure side blockage.

    What does the filter pressure gauge read?

    Have you checked all of the valves to make sure that the returns aren't turned off and the main valve is set to either filter or circulate? Try switching from filter to circulate and see anything changes.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Pump and Plumbing Diagnostics

    Some things to add here.

    I recently bought a new multiport valve because the old body had cracks all over it. I found that one lateral was cracked and there was barely enough sand in my filter to cover the laterals.

    The multiport valve is the only valve that is in my plumbing.

    There is no change with different valve settings. I have even disconnected the pump discharge between the pump and the filter and there is almost no flow out of the pipe.

    Since changing the multiport valve and replacing the pressure gauge it has always read 0.
    13,500 gallon IG fiberglass, 3/4hp pump, sand filter

  4. Back To Top    #4
    JasonLion's Avatar
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    Re: Pump and Plumbing Diagnostics

    That strongly suggests the issue is an air leak on the suction side of the plumbing.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    mas985's Avatar
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    Re: Pump and Plumbing Diagnostics

    3. Plumbed the pump suction into a large bucket full of water and opened the pump discharge so that I could see the flow.- Lots of water flowing from the pump
    4. Connected the suction plumbing back up and watched the flow from the pump.- Barely anything coming out of the discharge
    These two thing would indicate a suction side blockage to me.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  6. Back To Top    #6

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    Re: Pump and Plumbing Diagnostics

    I have replaced the plumbing shown in the attached picture. Nothing changed with the flow from the pump.



    Where else could I check for an air leak? I have replaced the filter lid o-ring and made sure it was lubed. Also as stated earlier I ran water over the lid with the pump running with no change.

    What could I do besides a shop vac blowing back to the skimmer to unblock the line?

    I appreciate all the help so far.
    13,500 gallon IG fiberglass, 3/4hp pump, sand filter

  7. Back To Top    #7
    JasonLion's Avatar
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    Re: Pump and Plumbing Diagnostics

    Have you tried using a drain king from the pump side and pushing back towards the skimmer? You sometimes need to remove the pump strainer basket to get good access to the input pipe.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  8. Back To Top    #8

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    Re: Pump and Plumbing Diagnostics

    I have not tried that. I will work on getting that done in the next day or two. How long should I leave the drain king in?
    13,500 gallon IG fiberglass, 3/4hp pump, sand filter

  9. Back To Top    #9
    JasonLion's Avatar
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    Re: Pump and Plumbing Diagnostics

    If nothing happens in a couple of minutes, it is very unlikely that longer will help.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  10. Back To Top    #10

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    Re: Pump and Plumbing Diagnostics

    Update:

    I put the drain king on the pump side blowing back to the pool. A couple of quick bubbles and then nothing. I could not feel any flow. I followed something from another thread on here and plugged the skimmer for 10-15 seconds and got a few leaves out of the line. I kept repeating this and got a couple of leaves everytime. Eventually I was able to fill about half of a grocery bag with leaves from the suction line. The line is now completely clear of debris from the skimmer through the 90. I put the shop vac back on the line and was getting tons of flow through the line. Connected everything back up and tried the pump; still no flow. I assume there are more leaves on the other side of the 90. I am going to repeat my efforts again this evening as long as the rain holds off. Thanks for the help.
    13,500 gallon IG fiberglass, 3/4hp pump, sand filter

  11. Back To Top    #11

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    Re: Pump and Plumbing Diagnostics

    Final update:

    I used a plumbing snake and the drain king and after a few tries was able to free up whatever was causing the problem. The pump is running better than it has since we have moved into this house. Thank you all for the help.
    13,500 gallon IG fiberglass, 3/4hp pump, sand filter

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