Oil Pressure Issues

[ayalar007]

Hey all....Its been a while since Ive posted on here because the old girl has been very very good. But this past week she started doing something that has stumped me. When I start her up in the morning I have 3 bars of pressure. When she warms up....it falls to 0. If I accelerate I get 3 bars. Took the oil cap off while idiling on 0 and there is plenty of oil on the cam lobes.....my question is....why am I getting a read out of 0? Is it the sending unit? I have replaced oil filter and oil all after it started doing it. I do not have access to a manual guage to check for a manual read out. Together with my dad we removed the oil pan this past weekend and looked at the pump. Everything looks a-o-k there. All the gears are perfect, the plastic tensioner for the chain is perfect there were no unidentified particles of any kind on the fileter mesh/filter. Can you all chime in and give me some suggestions? No one seems to know whats going on. All I know is that once you drive it the oil pressure is pegged at 3 and does NOT fluctuate. Is it that the pump is going south?