Low fuel pressure results in several issues for the engine, including rough idle, poor performance and decreased fuel economy. If the pressure is too low, the engine does not start. Fuel-injected engines are especially susceptible to problems with both fuel volume and fuel pressure.
Fuel pump and fuel pressure regulator problems lead to low fuel pressure. Mechanics use several different fuel pressure tests to determine the underlying cause. Most vehicles have a port to attach a fuel pressure gauge to the line for testing; manufacturers vary, however, in the particular test they recommend for specific vehicles. If the fuel pressure tests within specifications but the vehicle continues to fail to start, the problem is often with the fuel injectors.