The oil pump is in the timing cover and is accessible from outside the engine. It can be rebuilt.
The oil pick up assem. is inside the oil pan, either one can cause low oil pressure.
Pressure should be checked with a manual gauge to rule out bad oil pressure switch(sending unit).
My mechanic says there is oil flow but there is very little pressure. When we look in the valve cover where the oil goes in we can see very little oil with the engine running. Also found some very thin black flakes. Not sure of what to make of it. Any help or suggestions would be appreciated.