Digital mpg

What is your question?

I had a fuel pump replaced but since then the miles till the next fill up and the mpg average is screwy example: I can fill the tank and it will say about 350 miles till next fill, but as soon as i pull away from the pump that number may drop by about 20 or so mpg and the estimated mpg reads between 16.4 and 18.5 before the fuel pump i was around 24-25 mpg not sure if this drop is accurate or if its a computer problem