I have a mpi 454 with mi procharger it has the areomotive fuel system on it . When you key it the pump will biuld pressure but as soon as the pump stops the pressure drops unless the motor is running . Is this normal or am I getting air in there ?

my holley does the same thing..

Are AERO pump does the same thing.

Thanks for the feed back

I have two Bosch "044s" that required a good inline check-valve to keep pressure.. It still dies off over the period of a day, but it beats having to wait for the pump to pressure up to the rail/regulator after it was just running.

At one time, I had an A1000 that did the same and was fixed with a check. Just make sure the check is rated for the required flow.. (been there, done that, also)

Yup, normal as can be if you don't have check valves.