| Safety precautions when working on fuel supply system |
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| The fuel pressure in the high-pressure pipe can reach 120 bar! Observe the safety precautions when releasing pressure in the high-pressure section → Chapter. |
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| The fuel system is pressurised! Wear eye protection and protective clothing to avoid possible injury and skin contact. |
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| Before loosening line connections, wrap a cloth around the connection. Then release pressure by carefully pulling off line. |
| For reasons of safety, the power supply to the fuel pump must be interrupted before the fuel system is opened. The fuel pump would otherwise be activated when the driver's door is opened. Use the following options to interrupt the power supply: |
| Remove fuse for fuel pump control unit -J538-. |
| Pull off connector from fuel delivery unit flange or fuel pump control unit -J538- |
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Caution | When doing any repair work, especially in the engine compartment, pay attention to the following due to the cramped conditions: |
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| Route all the various lines (e.g. for fuel, hydraulics, activated charcoal filter system, coolant and refrigerant, brake fluid and vacuum) and electrical wiring in their original positions. |
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| To avoid damage to lines, ensure sufficient clearance to all moving or hot components. |
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| To prevent injuries to persons and/or damage to the injection and ignition system, the following must be observed: |
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| Do not touch or pull off ignition coils with output stage when engine is running or turning at starter speed. |
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| Switch off ignition before connecting or disconnecting injection and ignition system wiring as well as test instrument cables. |
| When removing and installing fuel gauge sender or fuel pump (fuel delivery unit) from a full or partly full fuel tank, observe the following: |
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| Even before work commences, the extraction hose of an activated fume extraction system has to be placed in the vicinity of the assembly opening of the fuel tank to extract any escaping fumes. If no exhaust gas extraction system is available, a radial fan with a displacement greater than 15 m3/h can be used providing that motor is not in air flow. |
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| Prevent skin contact with fuel! Wear fuel-resistant gloves! |
| Note the following if testers and measuring instruments have to be used during a road test: |
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| Test and measuring instruments must always be secured to rear seat and operated by a second person from this location. |
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| If test and measuring instruments are operated from front passenger seat and the vehicle is involved in an accident, there is a possibility that the person sitting in this seat may receive serious injuries when the airbag is triggered. |
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