You should start by checking fuel pressure, Your system should have a spec( Iam not at work and do not have a manual at home so i am not sure the spec)for how mush Psi the systwm should supply. Also you can check how much current draw the fuel pump is drawing. If it is out of spec it could be a wiring problem or a bad pump. There is also volume testing. This test will tell how much fuel is being pumped to the fuel rail. If you are not sure how do do these tests it is best to leave it up to a certifed Technician.