Steady low PSI, or total loss of flow/PSI. Seems lots of guys confuse fuel cavitation with LP failure, replace it with a new one, only to have the exact same jumping around of PSI issues as with the one replaced.
I had similar issues with mine, but was pretty sure it was cavitation rather than pump failure - so moved the LP to the frame rail close to my pusher pump. The difference in fuel flow and other contributing factors has to date totally eliminated my cavitation issue, and the OEM pump is still in use at 50K miles...