The fuel pump and fuel filter are the wrong place to look in trying to improve gas mileage. If there are interruptions in fuel flow, that's when you suspect fuel pumps or fuel filters.
A fuel filter is usually pretty cheap-about $5 and you can change it following the directions in Chiltons Auto Repair manual.
Fuel pumps can be a real bear to get at. Mechanical fuel pumps aren't too hard and may cost about $30. Your hands will get dirty. Electric fuel pumps are inside the gas tank and can be a major pain to get to. Get one from the dealer if it turns out you have a bad one- you don't want to use a cheap part you'll have to replace in a few years. Changing an electric fuel pump might be over your head if you never worked on cars or removed a gas tank from a car.
If you pay a barrel of money getting all this work done and still have bad driving habits, you will not see any gains in gas mileage.
Make sure the tire pressure is adequate. Put in a fresh set of sparkplugs if that hasn't been done for a couple of years. Replace the air filter.
