Fuel Supply System Safety Precautions
Note the Following When Working on the Fuel Supply:
There is a risk of injury because the fuel is under very high pressure.
- Reduce the fuel pressure down to residual pressure before opening high pressure area of the fuel injection system.
- To reduce the remaining residual pressure, lay a clean cloth around the connection point and carefully loosen the connection point.
-- Procedures before opening high pressure fuel injection system, refer to FUEL SUPPLY SYSTEM SAFETY PRECAUTIONS - "Releasing Pressure in High Pressure Area".
Burn risk due to escaping fuel.
- Because the Transfer Fuel Pump -G6- runs briefly when the battery is connected and the driver's door is opened, the voltage supply to the Transfer Fuel Pump -G6- must be disconnected before opening the fuel system.
-- Remove the fuse for the Fuel Pump Control Module -J538- inside the luggage compartment in the front and on the right side in Fuse Panel 3 -ST3-, refer to appropriate SYSTEM WIRING DIAGRAM.
To Prevent Personal Injury and Damage to the Injection and Ignition System, Observe the Following:
- The ignition must be switched off before connecting or disconnecting injection and ignition system wiring or tester cables.
- Wash the engine only when the ignition is turned off.
- Delete any DTC memory entries that occurred during testing or assembly, see Vehicle Diagnostic Tester, Check DTC memory , and then Generate readiness code .
Risk of damaging electronic components when disconnecting the battery.
- Observe the steps for disconnecting the battery.
- Always turn off the ignition before disconnecting the battery.
-- Disconnect the battery, refer to BATTERY, REMOVING AND INSTALLING .
Even Very Small Particles of Dirt can Cause a Fault. When Working on the Fuel Supply and on the Fuel Injection System, Observe the Following Guidelines for a Clean Working Environment:
- Before loosening, connections and surrounding areas must be cleaned thoroughly with engine or brake cleaner, and then cleaned area must be dried completely.
- Plug open lines and connections immediately with appropriate protective caps.
- Place the removed parts on a clean surface and cover them. Only use lint-free cloths!
- Install only clean parts: remove the replacement parts from their packaging just before installing them. Do not use parts that have been stored loose (for example, in tool boxes etc.).
- When the system is open: do not work with compressed air. Do not move vehicle unless absolutely necessary.
- Protect the disconnected connectors from dirt and moisture and only connect when they are dry.
Releasing Pressure In High Pressure Area
There is a risk of injury because the fuel is under very high pressure.
- The fuel injection system is separated into a high-pressure section (maximum about 120 bar (1740 psi)) and a low-pressure section (about 7 bar (101.52 psi)).
- Before opening high pressure components, for example removing the high pressure pump, fuel rail, fuel injectors, fuel pipes or Fuel Pressure Sensor -G247-, the fuel pressure in the high pressure area must be reduced to a residual pressure of approximately 7 bar (101.52 psi). The procedure for this is as follows.
Special tools and workshop equipment required
- Vehicle Diagnostic Tester
High Fuel Pressure, Reducing:
-- Connect a Vehicle Diagnostic Tester and perform "decrease fuel pressure" in "Guided Functions ".
- The fuel pressure reduces to a specified value.
-- Switch off the ignition.
The fuel rail will continue to be filled with fuel, but it will no longer be under high pressure.
Do not let fuel come into contact with skin.
- Wear protective eyewear and clothing when opening the fuel system.
- Lay clean cloths around the connection before opening the high pressure area to collect any fuel that leaks out.
-- After reducing fuel pressure, place a clean cloth around the connection and open the high pressure system >>immediately<<. Escaping fuel must be absorbed.
If the high pressure system is not opened immediately, the pressure will increase because of post-heating.
The ignition can no longer be switched on, otherwise the pressure will increase again.
Final Procedures
-- Erase the DTC memory and generate the readiness code in the engine control module in "Guided Functions ".