Just completed a complete engine rebuild w/ perf. upgrades to my Bosses `97 FLHT.Flushed oil tank,new oil lines,primed oil pump,lifters,oil filter,etc... Engine starts and as it builds oil pressure of 15-20 psi(2-3 seconds) it falls off to 0(5-10 seconds).Disconnected feed line from oil tank to pump,rotated it upwards and fed oil to pump from a funnel.Upon engine start it idled at 35psi and ran smooth and quite.Reattached feed line to oil tank,restarted and behold,same issue of press falling off .Fellas i need help with this one!