When I purchased my vette 3 years ago. I was getting an avg 22 MPG, which was great and a lot better than I expected. The fuel economy late last year dropped to 20 and then to 18 about a month ago. It was driving like crude and I was having fuel delivery issues. I replaced the fuel pump and then put new injectors on the car. Now the vette RUNS GREAT. But I have now dropped down to 17 MPG. I see posts of people reporting these crazy numbers. If this is normal, then I am happy because the car is running awesome but I do not want to be leaving money on the table if there is a hidden problem.

Thanks

 

You didn't list how many miles you have on it. Might be time for air filter, plug & wire change also.

 

Run a fuel pressure test....with and without the vacuum line attached.
Tape your fuel pressure gauge to your windshield and take a drive. (take a pencil and paper to record the readings)

You changed your fuel filter when you changed your fuel pump?