The first thing you want to do is test the fuel pressure to find out for sure if indeed the pressure is low. If it is then installing the fuel pump will not be to easy, you will have to lift the car and drop the tank. Depending on the manufacturer removing the tank will either be easy or hard. If you have never done it before I would reccomend letting your local mechanic do it. The fumes and the left over gas in the tank is very dangerous to deal with and any little spart or static charge could set the fumes off.