<strong>Fuel Pressure Regulator</strong><br />Well, we hate to say it, but this is another item that does exactly what the name implies. While the computer doesn't care what's going on with the fuel pressure regulator, for the most part, it plays a big role in things. The fuel pump listed above pumps at somewhere between 60 and eleventy billion psi. If the full eleventy billion psi was to go into the injectors, they'd simply explode. So the fuel pressure regulator cuts the pressure on the fuel line down to the specified 35-50 psi (depending on year/make/model) and is located on the fuel rail near the fuel line input or in the gas tank. This is important because the computer is preloaded with "maps," which allow the injectors to open for a certain amount of time. This amount of time that each injector opens (thus, allowing fuel into the engine) is based on a set pressure. Lower that pressure, and the engine runs lean. Raise it, and it runs rich. Again, attach a pressure gauge to the fuel rail to test for the correct pressure.