Fuel Supply System

Safety Precautions

Note the following when working on the fuel system:

There is a risk of injury because the fuel is under pressure.

• Place rags around the connection before opening the system. Then release pressure by carefully loosening the connection.

Very hot fuel can burn skin.

• For safety reasons, if the battery is "not" disconnected, the Fuel Pump (FP) control module (J538) fuse must be removed before opening fuel system. Otherwise, the fuel pump will be activated by the driver door contact switch.

• The temperature of the fuel lines or fuel may reach 100 °C (212 °F) after stopping the engine. Let the fuel cool down before opening any line connections otherwise there is a danger of scalding.

• Wear protective gloves.

• Wear safety glasses.

To prevent personal injury and damage to the injection and preglow system, observe the following:

• The ignition must be turned off before connecting or disconnecting injection and preglow system wiring or tester cables.

• Only clean the engine with ignition turned off.

• If the connectors were disconnected and the engine was started, then malfunctions have been stored in the Diagnostic Trouble Code (DTC) memory/engine control module: Query DTC memory under Guided Functions vehicle diagnostic tester.

Risk of destroying electronic components when disconnecting the battery.

• Observe measures for disconnecting battery.

• Only disconnect the battery with ignition turned off.

Disconnect the battery.

If testing equipment must be used during a road test, observe the following:

Distraction and testing equipment that is not secured properly can cause accidents.

The passenger airbag could pose a risk if it deploys in a collision.

• Operating testing equipment while driving causes it to shift position.

• There is an increased risk of injury due to unsecured testing equipment.

• Always secure testing equipment on the rear seat using a strap and have a second person in the rear seat operate it.

Note the following when removing and installing fuel tank components which are completely or partially filled:

The fuel tank may only be partially full. How much fuel can remain in the fuel tank may be read in the respective work description. Drain the fuel tank if necessary. Refer to => [ Fuel Tank with Reducing Agent Metering System, Draining ] Procedures

Before starting work, switch on exhaust extraction system and place an extraction hose close to the installation opening of fuel tank to extract escaping fuel fumes. If no exhaust extraction system is available, a radial fan (as long as motor is not in air flow) with a displacement greater than 15 m3/h can be used.

Prevent fuel from contacting skin! Wear fuel-resistant gloves!

When working on vehicles with the start/stop system, observe the following:

Danger of injury through automatic motor starting with vehicles with the Start/Stop System.

• For vehicles with an activated Start/Stop System (recognizable from a notification in the instrument cluster), the motor can be started automatically if needed.

• Thus, make sure that the Start/Stop System is disabled when working on the vehicle (turn off ignition, if needed, turn the ignition back on).