volvo penta 280 cooling issues

I can not get water through my out drive to my raw water pump. I ran water throug the intake hose off my pump to the outdrive with no problems but cannot get water up through outdrive to pump.

Any small air leak in the path to the sea water pump, will cause issues since anything upstream from the pump is undergoing suction.

Likely suspects:
Water neck fitting and special beaded gasket
S hose connection at same.
Lower pivot tube Oring
Suction hose breach
Scored or bad thrust surface and/or cam within the pump body
New impeller of incorrect type/size for the pump body (you do not list which engine or pump).

There are some issues with a Johnson and Jabsco impeller that looksidentical to one another, but are not.
This would be for a crankshaft style pump.