| The fuel pressure sender -G247- (rail pressure sensor) -1- is located in the left-side fuel rail (cylinder bank 2) and continuously measures the fuel pressure in the high-pressure system. It transmits a corresponding voltage signal to the engine control unit -J623-. |
| Should the sender fail, the engine control unit will control the fuel pressure via a mapped open-loop backup function, allowing a maximum of approx. 3000 rpm. |
WARNING | t
| Always read rules for cleanliness and instructions for working on fuel system → Chapter. |
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| Follow these instructions and rules for cleanliness before starting work and while working on the fuel system. |
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| Before removal, clean area around thread for fuel pressure sender using commercial cleaning solution etc. (no dirt must enter the opening in the rail). |
Note | Clean carefully; cleaning solution must not enter the electrical connector. |
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| Dry off fuel pressure sender -G247-. |
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| Unplug electrical connector at fuel pressure sender -G247-. |
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| Unscrew fuel pressure sender -G247-. |
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| Extract dirt from opening in rail (threads and sealing surface). Do not use metal tools, etc. |
Note | Seal off bore in rail immediately with a suitable plug to prevent dirt from entering. |
Note | t
| The fuel pressure sender -G247- does not have a seal; instead, it has a deformable sealing lip. |
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| Check that sealing surfaces (deformable sealing lip) and threads on fuel pressure sender -G247- are not damaged. If inspection of fuel pressure sender -G247- shows that it is OK, it can be used again. |
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| Also check sealing surface at opening in rail. |
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| The beginning of the thread and the deformable sealing lip of the fuel pressure sender -G247- must be lubricated with Molykote grease. |
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| Screw in fuel pressure sender -G247- by hand. |
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| Then tighten fuel pressure sender -G247- to specified torque. |
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| Tightening torque: refer to fuel system - exploded view → Chapter |
| Bleeding fuel system and checking for leaks |
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| After installation, run engine at moderate speed for several minutes and then switch off. |
Note | The fuel system is „self-bleeding“; do NOT open the high-pressure connections. |
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| Interrogate fault memory and erase, if necessary. |
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| Carefully check the entire fuel system for leaks. |
| Renew the affected component if leakage still occurs after tightening to the correct torque. |
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| After completing the repair, road-test the vehicle. Accelerate with full throttle at least once. Then check the high-pressure section of the fuel system again for leaks. |
Note | If there is any air left in the fuel system, the engine may switch to the backup mode ('emergency running' mode) during the road test. Switch off the engine and erase the fault memory. Then continue the road test. |
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| After road test interrogate the fault memory again. |
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