Fuel System Safety Precautions

WARNING: This page is about a different car, the 2015 Audi Q7, 2014 Audi Q7, and 2013 Audi Q7. However, it is still accessible from the selected car via links, so may be relevant.

Note the following when working on the fuel system:

WARNING:

Very hot fuel can burn your skin.

In extreme cases, the fuel lines and the fuel itself in vehicles with a common rail engine can be as hot as 100 °C (212 °F) after the engine has been turned off. Let the fuel cool down before opening any line connections otherwise there is a danger of scalding.
Wear safety gloves
Wear protective eyewear.

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

For safety reasons, if the battery is not disconnected, the Fuel Pump Control Module -J538- fuse must be removed before opening fuel system. Otherwise, the fuel pump will be activated by the driver door contact switch.
Place clean rags around the connection before opening the system. Then release pressure by carefully loosening the connection.
Wear safety gloves
Wear protective eyewear.

CAUTION:

Danger of causing damage to other electronic components when disconnecting the battery.

Complete the steps for disconnecting the battery.
Always turn off the ignition before disconnecting the battery.

-- Disconnect the battery. Refer to BATTERY, DISCONNECTING AND CONNECTING .

Follow the points below to avoid running the high pressure pump dry and to start the engine quickly after replacing the components:

CAUTION:

Letting the high pressure pump run dry will destroy it.

Follow the points below to avoid running the high pressure fuel pump dry and to start the engine quickly after replacing the components:
If fuel system components between the fuel tank and high pressure Fuel Pump (FP) were removed or replaced, the fuel system must be bled. Refer to FUEL SYSTEM, FILLING/BLEEDING .
If the high pressure FP was removed or replaced, then bleed the fuel system before starting the engine for the first time. Filling the fuel for the first time. Refer to FUEL TANK, FILLING WITH FUEL AFTER INSTALLING HIGH PRESSURE PUMP .

Clean the working area and tools before working on the injection system.
Before loosening, connections and surrounding areas must be cleaned thoroughly with engine or brake cleaner, and then cleaned area must be dried completely.
When disassembling, always cover any open connections immediately with clean caps.
Remove the caps from any components just before installing the component. Keep the parts that are going to used in a new, sealable plastic bag.
Check the fuel injector and locations for damage and dirt before installing. Make sure the shaft for the fuel injector is clean. Clean the injector shaft with a clean cloth if necessary without damaging it. Do not use any sharp-edged tools.
If the high pressure lines will not be replaced, mark them when removing. The high pressure lines must be installed again in the same cylinder.
Be careful not to damage the injector when removing the old copper seal.
Check all new O-rings for damage before installing. Lubricate the O-rings with assembly oil or engine oil before installing.
Align the high pressure lines free of tension. First tighten all connections hand-tight and then tighten them again to the tightening specification.
Never bend the high pressure lines.
It is permitted to use tools only for tightening and loosening the lines on the entire high pressure system. All other installation or removal procedures must be performed by hand without using any tools.
Press the fuel return hoses onto the injectors by hand and from the top until it audibly locks onto each injector (when doing this, do not press the release screw). Then press the release screw downward. Check the fuel supply hoses by pulling upward by hand for secure seating and for leaks.
Do not disassemble the individual Common Rail (CR) components. The complete component must be replaced if there is a malfunction.
Do not perform any work on the CR system while the engine is running at idle.
Do not bleed the CR system by loosening any high pressure components after starting the engine.
All cable ties which are opened or cut open when removing, must be replaced in the same position when installing.
Whenever the fuel system is open: avoid working with compressed air if possible. Do not move vehicle unless absolutely necessary.
In addition, do not let the diesel fuel flow onto the coolant hoses. If necessary, the hoses must be cleaned again immediately. Replace corroded hoses.