Fuel Pump Module

This procedure removes and replaces the fuel pump module assembly in the fuel tank, including depressurizing the fuel system, accessing the tank from inside the vehicle, and installing a new pump module.

Warnings

Tools required

Parts

• Fuel pump module assembly × 1 — A2214704594 or equivalent OEM
• Fuel pump lock ring seal/gasket × 1 — Use OEM specification
• Fuel line O-rings × 4 — Use OEM specification
• Access panel cover seal × 1 — Use OEM specification if damaged

Preparation

1. Park vehicle on level ground in a well-ventilated area away from ignition sources
2. Ensure fuel level is at 1/4 tank or less; if higher, use approved fuel extraction equipment to remove excess fuel from tank
3. Position Class B fire extinguisher within immediate reach
4. Disconnect negative battery terminal and wait 10 minutes for system capacitors to discharge
5. Remove rear seat cushion by pressing release tabs at front edge and lifting upward and forward
6. Remove rear seat backrest by unlatching center and side latches
7. Allow engine and exhaust system to cool completely (minimum 2 hours if recently driven)

Procedure

1. 1

   Relieve fuel system pressure
   Locate the fuel pressure test port on the fuel rail (driver side of engine). Remove the cap and attach a fuel pressure gauge with drain hose into an approved fuel container. Open the gauge valve slowly to bleed pressure. Continue until no more fuel flows and pressure gauge reads zero. Remove gauge and reinstall cap.
   ⚠️Fuel will spray under pressure. Ensure drain hose is securely in container and wear fuel-resistant gloves and eye protection.
2. 2

   Remove fuel pump access cover
   Locate the rectangular access panel in the floor beneath the rear seat (driver side). Remove the sound insulation material. Using appropriate driver, remove the access cover screws in a cross pattern. Carefully lift the metal access cover. Clean the area around the fuel pump opening thoroughly to prevent any debris from entering the tank.
   Torque spec

   Access Cover Screws5 Nm (4 lb-ft)
3. 3

   Disconnect electrical connector and fuel lines
   Disconnect the main electrical connector from the fuel pump module by pressing the release tab and pulling straight up. Identify the fuel supply and return lines. Using the appropriate fuel line disconnect tools, release the quick-connect fittings on both lines. Have absorbent pads ready as residual fuel will drain. Cap or plug open lines immediately to prevent contamination.
   ⚠Note the orientation and routing of fuel lines for correct reassembly. The S65 AMG has a high-flow fuel system; incorrect line connections will cause engine damage.
4. 4

   Remove fuel pump lock ring
   Install the Mercedes-Benz fuel pump lock ring tool onto the lock ring tabs. Note the alignment marks on the lock ring and tank flange. Using a breaker bar or long-handled wrench, turn the lock ring counterclockwise to loosen. The lock ring is torqued to 92 Nm and will require significant force. Once broken loose, unthread the lock ring completely by hand and remove it.
   ⚠Use only the proper lock ring tool. Do NOT use a hammer and punch, as sparks can ignite fuel vapors. Use brass tools if manual persuasion is needed.
   Torque spec

   Fuel Pump Lock Ring92 Nm (68 lb-ft)
5. 5

   Extract fuel pump module
   Carefully lift the fuel pump module assembly straight up and out of the tank opening. Tilt the module at an angle as it clears the opening to navigate the fuel level sender arm. The pump will have residual fuel in the reservoir; have a container ready. Once clear, place the old module in a fuel-safe container. Inspect the tank opening for debris and clean if necessary.
   ⚠The fuel level sender arm is fragile. Do not bend or force the module. Work slowly and tilt as needed to avoid damage.
   ⚠️Fuel will drip from the module. Keep all ignition sources away and have absorbent materials ready.
6. 6

   Inspect tank and prepare new module
   Using a flashlight, inspect the interior of the fuel tank for debris, rust, or contamination. If debris is present, use an approved method to clean (consult professional service if significant contamination exists). Remove the old lock ring seal from the tank flange and clean the sealing surface thoroughly. Unpack the new fuel pump module and verify all components are present. Install new O-rings on the fuel line connection ports, lubricating lightly with clean gasoline.
   Torque spec

   Fuel Line Fittings25 Nm (18 lb-ft)
7. 7

   Install new fuel pump module
   Position the new lock ring seal onto the tank flange, ensuring it seats properly in the groove. Carefully lower the new fuel pump module into the tank opening, tilting to navigate the fuel level sender arm through. Align the module with the alignment marks noted during removal. Press the module down firmly to seat it against the seal. Ensure the alignment tabs engage properly with the tank flange.
   ⚠The module must be properly oriented. Incorrect alignment will prevent the lock ring from threading and can damage the fuel level sender calibration.
8. 8

   Install and torque fuel pump lock ring
   Place the lock ring over the fuel pump module, aligning the threads with the tank flange. Thread the lock ring clockwise by hand until finger-tight. Install the lock ring tool and use a torque wrench to tighten to 92 Nm (68 lb-ft). Verify the alignment marks on the lock ring match the tank flange reference marks. The module should be firmly seated with no movement.
   Torque spec

   Fuel Pump Lock Ring92 Nm (68 lb-ft)
9. 9

   Reconnect fuel lines
   Inspect the quick-connect fittings on both fuel lines for damage or debris. Verify new O-rings are installed on the pump module ports. Push each fuel line onto its corresponding port until it clicks into place. Tug on each line to confirm it is locked. For threaded fittings (if applicable to your specific model variant), torque to 25 Nm using a flare-nut wrench.
   ⚠Confirm supply and return lines are connected to the correct ports. Cross-connection will cause immediate fuel system failure and potential engine damage.
   Torque spec

   Fuel Line Fittings25 Nm (18 lb-ft)
10. 10

    Reconnect electrical connector
    Inspect the electrical connector for corrosion or damage. Align the connector with the fuel pump module terminal and press firmly until it clicks into place. Ensure the connector lock tab engages fully.
    ℹ️A poor electrical connection can cause intermittent pump operation or limp mode activation.
11. 11

    Reinstall access cover
    Clean the access cover and surrounding area. Position the metal access cover over the opening, ensuring any alignment features are properly seated. Install the access cover screws and torque in a cross pattern to 5 Nm (4 lb-ft). Reinstall sound insulation material.
    Torque spec

    Access Cover Screws5 Nm (4 lb-ft)
12. 12

    Reconnect battery and prime fuel system
    Reconnect the negative battery terminal. Turn the ignition key to position II (on, but not starting) and listen for the fuel pump to run for approximately 3 seconds. Cycle the ignition off and on three times to prime the fuel system. Inspect all fuel line connections at the pump module for leaks. Check the fuel pressure test port area for leaks.
    ⚠️If any fuel leaks are observed, immediately turn off ignition, disconnect battery, and repair the leak before proceeding. Do not attempt to start the engine with a fuel leak present.
13. 13

    Start engine and verify operation
    Start the engine and allow it to idle. Monitor for smooth operation and listen for abnormal pump noise. The engine may run rough for the first few seconds as air purges from the fuel lines. Check for fuel leaks around all connections. Allow engine to reach operating temperature and verify no fault codes are present using a diagnostic scanner.
    ⚠If the engine fails to start, cranks excessively, or runs rough beyond initial startup, stop immediately and investigate. Do not continue cranking as this may damage the catalytic converters.

Reassembly

1. Reinstall rear seat backrest by engaging side latches and pressing center latch until it clicks
2. Reinstall rear seat cushion by hooking rear tabs and pressing front edge down until release tabs engage
3. Clear any diagnostic trouble codes that may have been set during the procedure
4. Test drive the vehicle under various load conditions to verify proper fuel delivery and no starvation under acceleration

Verification

• No fuel leaks present at pump module, fuel lines, or fuel rail connections
• Engine starts promptly and idles smoothly without hesitation
• No fuel pump whine or abnormal noise during operation
• No diagnostic trouble codes related to fuel system (P0087, P0230, P0461, etc.)
• Fuel gauge reads accurately and corresponds to actual fuel level
• Vehicle performs normally under full throttle acceleration with no fuel starvation or hesitation
• Access cover is secure with no fuel odor in passenger compartment

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