This is the stainless head with 3/4" center inlet. For a year now, the pump primes fine and will pump with ball valve 0-60% open. Any more than that and the water stops moving.
I have the same qd's as Kal, same pump, silicone hoses, but the only difference is it is mounted in a toolbox sitting on the floor instead of on a stand. Standard counter height to ground distance for pump inlet. There is not a pick up tube to contend with either.
I decided the problem must be the small qd's. I wanted a second pump anyway so bought the same one and equipped it with cam lock qd's. Just tried it and I have the same issue.
I have no problem priming the pump at all. It starts pumping immediately and will continue pumping until I try to open the valve all the way.
Ideas? I have a hard time believing it is the pumps. They were bought a year apart.
Edit: This happens with cold water as well as brewing temps. Thought I'd throw it out there since I've read of similar issues here but always only at boiling temp.