If the chain guides nylon pads were severely worn/damaged then there could be nylon pieces blocking the pickup screen (probably the problem). Also there is a rubber "O" ring that should be seated on the pickup tube right where the pickup tube enters the pump, just above the flange where the two 8mm bolts are seated to hold the tube on the pump. If it was missing then you will not prime. No need to prime the new pump. Yes, sometimes loosening the oil filter while cranking the engine will help relieve any airlock in the system.
Last edited by DYNOTECH; 10-19-2010 at 04:18 PM.