Working on an 04 4.6 DOHC engine, has been sitting 5 years, ran when pulled, now has no oil pressure when cranking. It will not fill oil filter. I have not started the engine, just filled with oil and cranked it over. The pick up has a good seal. Any suggestions appreciated.
Sometimes it's hard to get a modular oil pump to re-prime from cranking speed. People have reported removing the spark plugs to allow the motor's cranking speed to increase.
It's also possible that the oil pump spring pressure regulator is stuck.
Here's a link on how to use a common garden pressure sprayer to prime the motor. This could allow you to get the motor safely started while the oil pump primes. Obviously the oil pressure needs to be monitored in case it does not come up.