I have a 1999 454 Mag MPI that I replaced the water fuel separator, spark plugs. The first time it started it ran for about 20 seconds (till gas ran out of system) and then died. I've tried starting several times since then and it will only run for about 3-5 seconds and then dies.
Is there a purge in the MPI system that I need to know about to get the fuel running to the cylinders?

Remove the filter and fill it up from a gas can. It may take a few times to get it to prime. Fill up the filter, turn the key on and let the pump run. Cycle the key a few times and listen to the pump. If it starts to cavitate then stop and fill the filter again. Once the pump stops cavitating, then start the engine and it should be fine.
You really need to have some gas on hand in a gas can when you change the filter.
Eddie

Thank you Eddie! Worked like a charm.

Lee

I always prime my filters on my 502 mpi mags, I was told too if you dont it can hurt the fuel pump over time.