Fuel pressure is important for both performance and fuel efficiency. Maintaining proper fuel pressure under all operating conditions is the job of the fuel system. The PV350 provides critical fuel pressure readings on a multitude of fuel systems: carburetor, central point, throttle body injection or multipoint injection. Use it with the Fluke 78 to check the operation of fuel pressure regulators, fuel pumps and fuel pump check valves. Fuel pressures fall into two categories: high and low. Central point, or throttle body systems typically use low pressure (10-15 psi, 70-105 kPa). Most multipoint systems use a higher pressure (35-60 psi, 240-415 kPa). Low pressure during hard acceleration can indicate that a fuel filter is starting to clog.

Fig 10 - Testing Fuel System Pressure To test fuel pressure, use the schrader hose adapter with the PV500 to tap into the fuel rail. (If the vehicle doesn't have a schrader valve port, ask your local tool supplier for the appropriate adapter). Once you've taken your reading and before disconnecting the fitting, wrap a rag around it to catch any fuel spray. The safest way to do this is to disable the fuel pump and run the engine until it dies. Crank the engine a few seconds longer until all fuel pressure is relieved.