I take care of 12 commercial pools and have no problems priming any of them, although some are more difficult than others.
But today I came across one that I cannot get primed. Here is the details, 2 1HP motors with service factor of 1.65, Challenger pumps with a manual Jandy valve at the exit of each pump. The pool is about fifty feet from the pumps. I removed one motor that I thought was having problems and replaced with a known good motor the impeller, diffuser and seals all looked ok, but I replaced just to be sure. Fired it up and nothing changed.
I close both main drain and skimmers fill up both strainers with water and close lids tightly, turn on motors and barely open up main drain or skimmer (I've tried both ways) one side pulls a little stream of water for a couple of minutes the other side just seems to be bubbling. I've tried with jandy valves open and closed with no luck, primed over and over again even ran hose for ten minutes down the main drain and skimmer lines in attempt to remove air. This is not a new pool so it does work, I just took managing it over today.
Should I leave jandy valves open or closed when trying to prime? I've tried both ways to no avail, pump just sounds different when I change but get no water either way.