I recently fixed a starting problem with my 2007 VW Rabbit. I ended up replacing both the fuel filter and fuel injectors. After I was done, per the manuals directions, I flushed as much air as I could out of the fuel rail. Unlike the manual I did this by pressurizing the system using the driver side door which triggers the fuel pump. I probably got 3 to 4 cups of fuel out before the air was gone.
I noticed after a while though when purging the air that the fuel pump started making a higher pitch sound that I'd never heard from it. Now, after driving for about 5 miles, it still makes this higher pitch whine when pressurizing prior to starting via the front door trigger.
The car runs and starts great now, but I worry that something is going wrong with the fuel pump due to something I did. Perhaps I purged the air from fuel rail, but something is left in the pump motor? Is this something to worry about or will it resolve itself?