Pump primes and runs good, but won't self prime after it runs

Discussion in 'Irrigation' started by ErikWP, Apr 19, 2005.

  1. ErikWP

    ErikWP LawnSite Member
    Posts: 14

    I have a 1hp pump for a res. irrigation system. Shallow well 26 ft. I have replaced everything from the pump intake to the check-valve. Pump is a little hard to prime, and once it does prime it will run for 3 or more hours fine. Once the pump is off for a while, the preasure drops a bit and it will not self-prime. Need Help.
     
  2. crosson lawn

    crosson lawn LawnSite Member
    Posts: 107

    I have just had to mess with this also but it was my house pump and well! if it was my irrigation it wouldn't have made me so crazy. well you have a leak somewhere on the intake. all of that "good" glue job u did and plenty of thread tape well let me tell u there is a leak. i first thought there would be water leaking out but not true it has a suction on it so it is only letting air in. Here is what i did. i have a 1 1/4 inch well and pipe so i got a "t" with threaded sticking up so i could prime it and a 1 1/4 threaded plug (easier that a 3/4 to prime. i put this "T" at the point in the pipe that looked to be the highest point and filled it up. My pump also was having a hard time priming so i installed a spigot right there on the output and cracked it open and that does the trick everytime now. the air needed somewhere to go and there it is. oh yeah how to find the leak. dig up the whole line and where i put that plug in the "T" i adapted it to a air fitting and put a presure gauge there on it. i filled it up with air first to 50 lbs and then to 100. and then inspected the line and there it was right in one of my glue jobs air escaping. and i replaced that and tried it again and i had an air tight seal. that is how i will test all systems from now on i will air test it.
     
  3. ErikWP

    ErikWP LawnSite Member
    Posts: 14

    Could the air leak be in the discharge line. I have a 20' well pvc well point.
    At the op there is a check-valve, above that it elbows to the pump.
    COming out the pump is a four-way galvanized, with a spicket on the end, an air tank on the top, and the discharge going down. The discharge connects to another spicket and then to the irrigation system.
     
  4. crosson lawn

    crosson lawn LawnSite Member
    Posts: 107

    no the air leak is definitely on the intake. when trying to prime open a discharge line to let the air out and to draw the water up.
     

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