86 Camaro bad gas mileage

Hi im 16 and know very little about cars, but I have a camaro that I have been working on I replaced the fuel pump because it was leaking and I was getting bad gas mileage. I was hoping this would fix it. Theres no longer a puddle of gas under my car but it still only gets about 6-8 miles to the gallon. Anyone have any ideas of what to do?

is the car manual or automatic?
which engine does it have?
how many miles on it?
have you done a tuneup?
air filters?
fuel filter?
O2 sensor?

just a little background info to help in diagnosis.

many many miles changed the filters never did a tune up.

First thing i would try is a general tune up...

Check the base timing
new sparkplugs
new cap and rotor
new plug wires
induction service
and a can of fuel injector cleaner in the tank.

drive it for a few weeks and see if the problem has been fixed.