hi i have a 91 z28 with a 305 tpi, when i bought the car the fuel pump started to whine. so i bought a new one along with strainer and fuel filter, installed everything and after 2 days the new fuel pump starts to whine (ac delco pump). i check the evap system and its working. when i take the gas cap off NO air comes out or hissing nosie. so its dosnt seem its a pressure issue. btw the car has a bad egr valve and runs alittle rich. i did valve seals on it and adjusted the valves. i have 2 injectors that read 14volts and 6 that read between 9-12 volts.