Leaving off the inducer can cause cavitation problems that will interfere with the head. The impeller is loose on the shaft. The shaft is running backwards because of a wiring problem. The pump is running backwards because the discharge check valve is not holding and system pressure is causing the reverse rotation. This is a common problem with pumps installed in a parallel configuration.
Check valves are notoriously unreliable.
The impeller has been installed backwards. This can happen with closed impellers on double ended pumps The second stage of a two stage pump is wired backwards. The pump reverses when the second stage kicks in. You should have heard a loud noise when this happened. The wear ring clearance is too large.