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Fuel System Pressure Check

WARNING: Working on the fuel system results in fuel and fuel vapor being present in the atmosphere. Fuel vapor is extremely flammable, hence great care must be taken while working on the fuel system. Adhere strictly to the following precautions: Do not smoke in the work area Display NO SMOKING signs around the work area Disconnect the battery before working on the fuel system Avoid sparks Make sure suitable fire extinguishers are at hand Make sure absorbent material is at hand to soak up any spillage Make sure the work area is well ventilated Make sure that the gauge is correctly connected, and that all connections are secure BEFORE starting the engine DO NOT disconnect the gauge from the schrader valve while the engine is running Make sure the schrader valve reseals once the gauge is disconnected.
  1. Make sure the vehicle is in Park for vehicles with automatic transmission, Neutral for vehicles with manual transmission.
  2. Apply the parking brake.
  3. Place suitable absorbent material around the schrader valve to absorb any spillage when connecting the gauge set.
  4. Remove the protective cap from the schrader valve.
    5. NOTE: Depending on the design of the gauge set, there may be a drain valve and tube. Make sure this valve is closed, and the drain tube placed in a suitable container BEFORE connecting the gauge to the schrader valve.
  5. Connect the gauge, using adaptors if required.
  6. Remove the absorbent material and dispose of safely.
  7. Disconnect and plug the vacuum hose from the pressure regulator.
  8. Start the engine and record the fuel pressure reading.
    • As a guide, the fuel pressure should be approximately 3.0 bar (44.1 psi) with the regulator disconnected.
  9. With the engine still running, reconnect the vacuum hose to the pressure regulator and record the reading.
    • The pressure should drop to approximately 2.6 bar (38 psi) when the vacuum hose is reconnected.
  10. Switch off the engine.
  11. Place more absorbent material around the schrader valve.
  12. Where fitted, open the drain valve and allow the fuel from the gauge and line to flow into the container to depressurize the system.
  13. Disconnect and remove the gauge set and any adaptors.
  14. Clean up any fuel which may have been spilt and remove the absorbent material. Dispose of safely.
  15. Refit and secure the protective cap to the schrader valve.
  16. Reconnect the fuel pressure regulator vacuum hose.
  17. Start the engine and make sure there are no leaks.
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