I rebuilt this engine and seem to have some type of problem with the oil pump or something. After the engine sits for a day or so when it is cranked the low oil pressure alam sounds. THe oil seems to be draining from the pump and it has a hard time repriming and providing. This doesn't make any since but if I remove the oil filter the pump will reprime itself and everthing is ok until it sits for a day or so again - then same issue. The oil pump is new and the engine oil pressure is within specs when it primes and runs. Am I missing something ? CAn you have a vapor lock ? I'm stumped - Need help with this one