General
General function description for fuel systems. See Function Description .
Parts Designation
| 1. Fuel tank (plastic) | 15. Expansion tank |
|---|---|
| 2. Electric fuel supply pump | 16. Antiflood valve |
| 3. Pressure limiting valve | 17. Roll-over valve |
| 4. Non-return flap | 18. Pressure regulator |
| 5. Filler pipe | 19. Fuel filter |
| 6. Tank expansion line | 20. Fuel rail |
| 7. Suction jet pump | 21. Tank vent valve |
| 8. Outlet protection valve | 22. Engine control unit |
| 9. Tank cap | 23. Intake manifold |
| 10. Fuel feed line | 24. Purge line |
| 11. Fuel return line | 25. Carbon canister |
| 12. Refueling vent line | 26. Evaporation line |
| 13. Service vent line | 27. Tank leakage diagnostic module |
| 14. Pressure test line (USA only) | 28. Dust filter |
| (1) (Scheme 60) | |
| (1) | (Scheme 60) |
PARTS DESIGNATION (1)
Fuel System
The saddle-shaped fuel tank contains the electric fuel supply pump in its smaller right half.
The suction jet pump in the left fuel tank half pumps the fuel through the tank expansion line to the right side of the fuel tank.
The suction jet pump is operated via the fuel feed line.
The pressure limiting valve controls the pressure required to operate the suction jet pump. The outlet protection valve protects the fuel return line. The valve closes in the event of a pressure drop when the fuel return line is damaged or disconnected.
This prevents fuel from escaping from the fuel tank in extreme vehicle positions (overturning, inclined position).
The non-return flap prevents fuel from splashing back in the filler pipe after shutdown of the petrol/gas pump nozzle.
The antiflood valve on the underside of the expansion tank protects the system against overfilling during refueling. The antiflood valve is closed by the fuel rising in the refueling vent line, thereby generating an overpressure in the fuel tank, which in turn prevents further filling.
Fuel Supply To Engine
Pressure regulator and fuel filter are incorporated in a single unit.
The fuel is routed from the electric fuel supply pump via the fuel feed line and the fuel filter/pressure regulator unit to the fuel rail.
The fuel rail is return-free. The fuel flows directly from the fuel filter/pressure regulator unit back into the fuel tank.
Venting System USA
The fuel tank is vented during refueling via the refueling vent line.
Because of its large cross-section, the refueling vent line directs the displaced volume (fuel vapors) at high speed through the expansion tank to the carbon canister.
The activated carbon retains the fuel contained in the fuel vapors. The cleaned air is discharged to atmosphere via the evaporation line, the tank leakage diagnostic module and the dust filter.
During driving, the system tank is vented in the same way via the refueling vent line and service vent lines.
The condensed constituents of the fuel vapors pass from the expansion tank via the vent lines back into the fuel tank.
The roll-over valve on the upper side of the expansion tank closes in the event of the vehicle overturning. This prevents the fuel from escaping into the carbon canister.
The carbon canister is regenerated by purging with fresh air.
The engine control unit opens the tank vent valve. Thus the vacuum pressure of the engine intake manifold is applied at the purge line.
In this way, the carbon canister is purged by the supply of fresh air via the tank leakage diagnostic module and the dust filter. The fuel constituents bound by the activated carbon are flushed out by the supplied air and directed via the purge line to the engine for combustion.
This operation is only possible while the engine is running.
Leakage Detection For Tank Venting System USA
The tank leakage diagnostic module serves to detect leakages for the tank venting system within the on-board diagnosis laid down by legislation.
The tank venting system is pressurized and the pressure loss is detected in the event of a leak.
The tank leakage diagnostic module is activated by the engine control unit and detects the pressure loss by way of the power consumption of the integrated pump. The air required for this purpose is supplied via the dust filter.
The pressure test line establishes the connection between fuel tank and filler neck. This enables a leak to be detected in the filler pipe - tank cap area.
Determining Fill Level In Fuel Tank
The fuel level is measured by means of lever-type sensors on both sides of the fuel tank. The right lever-type sensor is integrated in the fuel supply unit. The left lever-type sensor is located in the left sensor unit. The combination of the determined ohm values from the right and left lever-type sensors produces the actual level in the fuel tank.
Service Data, Fuel System
Pressure regulator: 3.5 bar.
Working pressure of suction jet pump: 1 - 1.3 bar
Scheme 60
Fuel Supply Systems, Spark-Ignition Engines
Fuel system
The electric fuel pump in the fuel tank generates the pressure in the fuel system which is set by the pressure regulator to a specific level.
Tank venting system
The tank venting system is an enclosed system which is vented via a carbon canister. The carbon is incorporated in the carbon canister as granulate. The large surface of the carbon stores the fuel vapors which occur in the fuel tank. The carbon canister must be regenerated on a regular basis so as to be able to continue storing fuel vapors. Regeneration is performed by way of purging with fresh air via the intake manifold. This process is controlled by the engine control unit.
16 00 005 Draining and filling fuel tank
| CAUTION | Observe relative country safety legislation and regulations! Ensure adequate ventilation in the place of work! Connect exhaust extraction unit to exhaust tailpipe. The electric fuel pump must not operate without fuel! After completing repairs and before starting engine for first time, fill fuel tank through fuel filler pipe with min. 5 ltr. fuel. Do not damage non-return flap when pulling out extraction hose. |
Drawing Off Fuel
Start engine and allow to run. Electric fuel supply pump runs.
In this way, the fuel is repumped through the suction jet pump and the tank expansion line from the left to the right side of the fuel tank.
Note. Fuel can be drawn off from the left and right tank halves through the fuel filler pipe down to a small residual amount. This residual amount is drawn off after removal of the sensors for the fuel gauge (right/left).
Slide extraction hose of extractor unit into filler pipe, turning hose slightly if necessary.
Insertion Length
150 cm
Draw off fuel with extractor unit
as far as possible.
Follow the fuel drawing-off procedure at the fuel gauge in the instrument cluster.
Scheme 61
Drawing Off Residual Fuel Quantity
| CAUTION | Ensure car interior is adequately ventilated. Catch dripping fuel in a suitable container. |
Remove sensor for fuel gauge (right).
Remove sensor for fuel gauge (left).
Draw off residual fuel quantity through installation openings.
Fuel Filling
Slide extraction hose of extractor unit
approx. 40 cm into filler pipe.
Fill fuel from extractor unit.
Scheme 62
Drawing Off After Fault In Suction Jet Pump
Draw off right half of tank completely through filler pipe.
Remove sensor for fuel gauge (left).
Insert extraction hose through sensor opening in tank, fuel (also residual quantity) can be drawn off.
Scheme 63
16 00 100 Checking fuel tank and tank ventilation system for leaks
Special tools required
- 13 3 010
- 16 1 157
- 16 1 171
- 16 1 174
Leak Test
Note. The following procedure is only applicable to vehicles without the tank leak diagnosis module.
Check tank venting system if a leak is suspected.
The following conditions must be observed to obtain plausible measuring results
- Content of fuel tank: Max. 90% (approx. 83 l) Min. 13% (approx. 12 l, reserve indicator lamp "off").
- Park the car in the workshop at least 2 hours before the test so that the fuel temperature is approximately that of the workshop temperature (ideal fuel temperature approx. 10...20°C).
- Never refuel the vehicle directly prior to the leak test due to the strong emission of gas by the fresh fuel.
Removing fuel tank underbody protection on left.
Unlock connection (3) on carbon canister and detach.
Using special tool 16 1 157, seal opening for connection (3) on carbon canister.
Scheme 64
Remove tank cap and connect special tool 16 1 174 to tank filler neck.
Using adjusting wheel (1), clamp special tool 16 1 174 firmly to tank filler neck.
Scheme 65
| CAUTION | Set pressure regulator on special tool 16 1 171 fully in "-" direction. |
Connect special tool 16 1 171 using compressed air line (1) to garage compressed air system (8...10 bar).
Connect pressure sensor (2) of Diagnosis and Information System with measuring range of 0...3.5 bar.
| CAUTION | Do not connect fast-release coupling (3) of special tool 16 1 171 yet. |
Scheme 66
Select "Measurement" function on Diagnosis and Information System (DIS).
Set measuring range in accordance with pressure sensor to 0-3.5 bar.
Using pressure regulator on special tool 16 1 171, increase pressure by 0.050 bar.
Connect special tool 16 1 174 to fast-release coupling of special tool 16 1 171.
Using pressure regulator on special tool 16 1 171, reset gauge pressure in fuel tank to 0.050 bar.
| CAUTION | Do not under any circumstance increase pressure by more than 0.100 bar as this would result in damage to the fuel tank and venting system. |
Using special tool 13 3 010, disconnect supply line from special tool 16 1 171 to tank filler neck.
Allow a rest period of approx. 20 secs.
Read off and note down starting pressure value.
Wait 60 secs.
Read off final pressure value and compare with starting pressure value.
Measurement Evaluation
| Pressure drop between 0.008 and 0.010 bar. | Measure again. |
|---|---|
| Pressure drop in 60 secs. greater than 0.010 bar | System leaking beyond permitted levels. Carry out leak test. |
MEASUREMENT EVALUATION
16 00 102 Checking fuel tank and tank venting system for leaks with tank leakage diagnosis module (DM-TL)
Note. An OBD fault is indicated by the "Check Engine" indicator lamp in the instrument cluster lighting up. This may indicate a leak in the tank venting system. Information on this is provided by the fault memory of the DME control unit.
Adhere to following conditions in order to carry out a correct leak test
- Read out fault memory of DME control unit and carry out a diagnosis in accordance with faults stored.
- A leak test with the DM-TL module is then carried out if: The components of the DM-TL module are O.K. A error is stored in the DME fault memory (tank leak detected).
- Content of fuel tank < 90%
- Reserve indicator lamp "off"
- Park the car in the workshop at least 2 hours before the test so that the fuel temperature is approximately that of the workshop temperature (ideal fuel temperature approx. 10...20°C).
- Never refuel the vehicle directly prior to the leak test due to the strong emission of gas by the fresh fuel.
- Check that tank cap is correctly seated.
| WARNING | During the leak test, under no circumstance apply external pressurization through the tank filler neck as this may cause incorrect readings. |
Clear DME fault memory.
Select function "Service functions" on Diagnosis and Information System (DIS).
From the "DME system check" menu, select the tank leak system check DM-TL; leak test is carried out.
If a fault is stored again in DME fault memory (tank leak detected), carry out leak testing.
16 00 510 Conducting leak test on fuel tank and tank ventilation system
Note. The following procedure is only applicable to vehicles with the tank leak diagnosis module (DM-TL).
- Select "4 Expert mode" function on Diagnosis and Information System (DIS).
- From the menu "2 Activate components", select the function "118 Tank leak diagnosis E53: DMTL pump". Following appears in display: DMTL pump; pump is activated.
- Tank leak diagnosis pump pressurizes fuel tank and tank venting system.
For vehicles without tank leak diagnosis module: Pressurize through filler neck.
When leak-testing with a leak detector: follow manufacturer's operating instructions.
| CAUTION | On vehicles with tank leak diagnosis modules (DM-TL), do not work with external pressurization as the tank venting system will leak under this condition. On account of emerging fuel vapors, carry out all work in well ventilated rooms. Or use a suitable extractor system. Observe country-specific accident prevention and occupational safety regulations. |
The leak test can be carried out with a leak detector.
Possible causes may be
Scheme 67
- Tank cap leaking (check tank cap pressure relief valve).
- Tank venting lines leaking (fuel tank - carbon canister - tank venting valve).
- Tank venting valve leaking (engine compartment)
- Fuel level sensor flange on tank leaking
16 11 130 Checking filler cap pressure relief valve
Special tools required
- 13 3 010
- 16 1 171
- 16 1 172
- 16 1 173
Pressure Test
Set pressure regulator on special tool 16 1 171 fully in "-" direction.
Connect special tool 16 1 171 via compressed air line (1) to garage compressed air system (8...10 bar).
Connect pressure sensor (2) of Diagnosis and Information System with a measuring range of 0...3.5 bar.
Scheme 68
Select special tool 16 1 172 or 16 1 173 matching vehicle's filler cap and attach to quick release coupling of special tool 16 1 171.
Install filler cap on selected special tool (3).
Scheme 69
Note. Only the absolute pressure is indicated in the display of the Diagnosis and Information System (DIS). The current ambient air pressure is already displayed without additional pressurization.
Checking Test Equipment For Leaks
Select "Measurement" function on Diagnosis and Information System (DIS).
Set measuring range according to pressure sensor to 0-3.5 bar.
Increase pressure by 0.2 bar with pressure regulator on special tool 16 1 171.
Using special tool 13 3 010, disconnect delivery line from special tool 16 1 171 to tank filler neck.
Wait 60 secs.
Read off final pressure value and compare with starting pressure value.
| Pressure drop > 0.012 bar | Testing equipment leaking. Check connection points for leaks. |
MEASUREMENT EVALUATION
Check Filler Cap Pressure Relief!
Follow same test procedure as for "Checking testing equipment for leaks".
Increase pressure by 0.3 bar with pressure regulator on special tool 16 1 171.
| Pressure drop > 0.012 bar | Filler cap pressure relief valve faulty. Replace filler cap. |
MEASUREMENT EVALUATION
16 11 030 Removing and installing fuel tank
| CAUTION | After installation of fuel tank/prior to first engine start-up: Check electrical resistance between grounding lead (fuel tank filler pipe) and wheel hub. Measured value: approx. 0.6 Fill fuel tank with at least 5 liters of fuel. |
Draw off fuel from fuel tank
refer to 16 00 005 DRAINING AND FILLING FUEL TANK .
With special tool 34 1 030, unfasten lock nut. Screw down lock nuts and adjusting nuts completely from handbrake cables.
Installation
Adjust handbrake
refer to PARKING BRAKE .
Scheme 70
Remove rear seat bench
refer to 52 24 005 REMOVING AND INSTALLING / REPLACING REAR SEAT .
Scheme 71
Remove rubber plugs (1).
Scheme 72
Fold back rubber mat (1).
Release screws (2) and (3).
| CAUTION | Do not damage gasket. |
Fold back metal covers.
Scheme 73
Left fuel tank half
Disconnect plug connection (1) on fuel level sensor.
Scheme 74
Right fuel tank half
Disconnect plug connection (1) on delivery unit.
Release hose clamp (2), detach fuel tank vent line.
Replace hose clamp.
Tightening Torque, refer to FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Scheme 75
Remove propeller shaft completely
Removing Fuel Tank Underbody Protection On Left
Release metal screws (1).
Unfasten screws (2).
Scheme 76
Release screws (1) on wheel arch trim on left.
Scheme 77
Bend open wheel arch trim.
Release screw (1).
Scheme 78
Release screws (1).
Scheme 79
Remove screws (1 and 2).
Unscrew nuts (3).
Remove fuel tank underbody protection on left towards bottom.
Scheme 80
Removing Fuel Tank Underbody Protection On Right
Release metal screws (1).
Unfasten screws (2).
Scheme 81
Release screws (1) on wheel arch trim on right.
Scheme 82
Bend open wheel arch trim.
Release screw (1).
Scheme 83
Release screws (1).
Scheme 84
Release screws (1).
Remove fuel tank underbody protection on right towards bottom.
Scheme 85
Unclip handbrake cables (1) and remove from guide tubes.
Scheme 86
Remove fuel filter (1)
refer to 13 32 051 REPLACING FUEL FILTER .
Scheme 87
Note. If necessary, only fuel feed and return lines can also be disconnected from fuel filter. Release screws, open clamps (2) and detach fuel filter from fuel tank.
Scheme 88
Note. Unlock connection on carbon canister with special tool 16 1 050.
Detach connection (1) (filling vent).
Scheme 89
Remove rear right wheel
refer to WHEEL AND TIRES - REPAIR INSTRUCTIONS .
Remove rear right wheel arch trim.
Scheme 90
Release hose clamp (1) and detach hose (2) from fuel tank (3).
Replace hose clamp.
Tightening Torque, refer to FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Scheme 91
Mark following lines before and after separation point (adhesive tape).
Scheme 92
- Overflow dia. 8 mm
- Fuel tank vent dia. 8 mm
- Overflow dia. 8 mm
- Tank vent dia. 18 mm
- Filling vent dia. 18 mm
Open hose clamps so that no hose clamp has to be pulled through wheel arch aperture.
Example "Tank Vent"
Unfasten hose clip (1).
Do not release hose clamp (2).
Detach lines from hoses.
Scheme 93
Replace hose clamps.
Tightening Torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Tightening Torque, refer to 16 12 9AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Support fuel tank on left fuel tank half.
Note. When supporting fuel tank, tightening straps must not be covered.
Scheme 94
Release screw (1) for fuel tank mounting, rear right.
Tightening Torque, refer to 16 11 130 CHECKING FILLER CAP PRESSURE RELIEF VALVE .
Unhook and remove tightening strap.
Scheme 95
Release screw (1) for fuel tank mounting, rear left.
Tightening Torque, refer to 16 11 130 CHECKING FILLER CAP PRESSURE RELIEF VALVE .
Scheme 96
Release screw (1) for fuel tank mounting, center.
Tightening Torque, refer to 16 11 130 CHECKING FILLER CAP PRESSURE RELIEF VALVE .
Unhook and remove tightening straps.
Scheme 97
Note rubber mount with spacer bush on tightening strap screw connections.
Wide collar on spacer bush faces towards screw head.
Scheme 98
Note shim on both locating lugs.
Scheme 99
Carefully lower fuel tank approx. 20 cm.
Scheme 100
Remove line bundle (1) from wheel arch.
Carefully lower fuel tank further and set down.
Scheme 101
16 11 031 Replacing fuel tank
Remove fuel tank
refer to 16 11 030 REMOVING AND INSTALLING FUEL TANK .
| CAUTION | Do not damage fuel lines. |
Remove fuel gauge sensors on right and left.
These work steps are described on an installed fuel tank
Open hose clamps on following fuel lines
Scheme 102
- Vent (to expansion tank, bottom)
- Overflow (to expansion tank, top)
- Overflow (to expansion tank, bottom)
- Filling vent (to expansion tank, top, and to carbon canister)
- Tank vent (to expansion tank, bottom)
Disconnect fuel lines from fuel tank.
Do not damage fuel lines.
If necessary, lay a new fuel line bundle without kinks.
Replace hose clamps.
Tightening Torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Tightening Torque, refer to 16 12 8AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
If necessary, remove fuel filter (1) from fuel tank (Scheme 103)
Scheme 103
Open hose clamps on following fuel lines
Scheme 104
- Fuel feed line
- Fuel return line Disconnect lines from fuel tank.
Do not damage fuel lines.
If necessary, lay new fuel lines without kinks.
Replace hose clamps.
Tightening Torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
16 11 050 Removing and installing/replacing all fuel lines on fuel tank
Remove fuel tank
refer to 16 11 030 REMOVING AND INSTALLING FUEL TANK .
Note. Contrary to illustrations below, fuel gauge sensors on right/left are not removed.
Open hose clamps on following fuel lines
Scheme 105
- Vent (to expansion tank, bottom)
- Overflow (to expansion tank, top)
- Overflow (to expansion tank, bottom)
- Filling vent (to expansion tank, top, and to carbon canister)
- Tank vent (to expansion tank, bottom) Disconnect fuel lines from fuel tank.
Do not damage new line bundle.
Lay line bundle without kinks.
Replace hose clips.
Tightening torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Tightening torque, refer to 16 12 8A in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES Z.
If necessary, disconnect fuel feed and return from fuel filter.
Open hose clamps on following fuel lines
- Fuel feed line
- Fuel return line
Disconnect fuel lines from fuel tank.
Scheme 106
Do not damage fuel lines.
Lay fuel lines without kinks.
Replace hose clips.
Tightening torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
16 11 060 Removing and installing or replacing fuel filler pipe
Unhook retaining strap (1) from tank flap.
Open cap and set to one side.
Draw off fuel from fuel tank
refer to 16 00 005 DRAINING AND FILLING FUEL TANK .
Scheme 107
Remove rear right wheel
Remove rear right wheel arch trim.
Scheme 108
Unfasten hose clip (1).
Replace hose clamp.
Tightening Torque, refer to 16 12 9AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Detach hose (2) from fuel tank (3).
Scheme 109
Release plastic nuts (1).
Scheme 110
Slacken nut (1).
Withdraw fuel filler pipe (2) completely out of rubber gaiter at wheel housing.
Scheme 111
| CAUTION | After installing fuel filler pipe, check electrical resistance between grounding lead (tank filler pipe) and wheel hub. Measured value: approx. 0.6 ? |
Unfasten hose clip (1).
Replace hose clamp.
Tightening torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Detach vent line (2) with hose (2) from fuel filler pipe (3).
Scheme 112
16 11 120 Removing and installing / replacing expansion tank for tank ventilation
Remove rear right wheel
Remove rear right wheel arch trim.
Scheme 113
Release hose clamps and detach lines from expansion tank at bottom.
- Fuel tank overflow
- Fuel tank vent
- Tank vent
Replace hose clamps.
Tightening Torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Tightening Torque, refer to 16 12 8AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Scheme 114
Release nuts (1).
Tightening Torque, refer to 16 13 1AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Lower expansion tank (2).
Scheme 115
Release hose clamps and detach lines from expansion tank at bottom
Scheme 116
- Filling vent
- Fuel tank overflow
Replace hose clamps.
Tightening Torque, refer to 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Tightening Torque, refer to 16 12 8AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES .
Remove expansion tank.
Special tools required
Scheme 117
- 13 3 010
- 16 1 171
- 16 1 172
- 16 1 173 Set pressure regulator on special tool 16 1 171 fully in "-" direction. Connect special tool 16 1 171 via compressed air line (1) to garage compressed air system (8...10 bar). Connect pressure sensor (2) of Diagnosis and Information System with a measuring range of 0...3.5 bar.
Select special tool 16 1 172 or 16 1 173 matching vehicle's filler cap and attach to quick release coupling of special tool 16 1 171.
Install filler cap on selected special tool (3).
Scheme 118
Note. Only the absolute pressure is indicated in the display of the Diagnosis and Information System (DIS). The current ambient air pressure is already displayed without additional pressurization.
Check Testing Equipment For Leaks!
Select "Measurement" function on Diagnosis and Information System (DIS).
Set measuring range according to pressure sensor to 0-3.5 bar.
Increase pressure by 0.2 bar with pressure regulator on special tool 16 1 171.
Using special tool 13 3 010, disconnect delivery line from special tool 16 1 171 to tank filler neck.
Wait 60 secs.
Read off final pressure value and compare with starting pressure value.
| Pressure drop > 0.012 bar | Testing equipment leaking. Check connection points for leaks. |
MEASUREMENT EVALUATION
Follow same test procedure as for "Checking testing equipment for leaks".
Increase pressure by 0.3 bar with pressure regulator on special tool 16 1 171.
| Pressure drop > 0.012 bar | Filler cap pressure relief valve faulty. Replace filler cap. |
MEASUREMENT EVALUATION
16 12 000 Removing and installing/replacing sensor for fuel level gauge (right)
| IMPORTANT | Ensure adequate ventilation in the place of work! |
Ensure absolute cleanliness when working on the open fuel tank.
Contaminants in the fuel tank can impair driving operation or may even result in vehicle breakdown!
Necessary preliminary tasks
- Draw off fuel from fuel tank
- Remove rear seat bench
Detach rubber plug above sensor unit on right.
Fold back rubber mat.
Scheme 119
| IMPORTANT | Do not damage gasket. |
Release screws (1) and fold back metal cover.
Scheme 120
| IMPORTANT | Fuel hoses are pressurized. |
Unlock plug connection and disconnect.
Force off hose with a clamp.
Release hose clamp (1) and carefully detach hose. Do not damage connecting piece when doing so.
Independent heating only
Force off hose with a clamp.
Release hose clamp (2) and carefully detach hose. Do not damage connecting piece when doing so.
Installation
Replace hose clamps.
Tightening torque see 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES
Scheme 121
Release screw cap with special tool 16 1 020.
Replace rubber gasket.
Tighten down screw cap to specified torque.
Tightening torque, see 16 14 2AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES
Scheme 122
Carefully raise fuel level sensor until sensor flange projects out of sealing area of tank opening.
In so doing, do not pull excessively on connecting piece of fuel feed. Risk of breakage!
When installing fuel level sensor, make sure that lug (1) in opening (2) engages fuel tank.
During torque tightening, notch (3) on screw cap can be clearly heard and felt to engage toothed segment (4) on fuel tank.
Scheme 123
| IMPORTANT | Do not bend sensor. |
Carefully raise fuel level sensor (1) and expose spiral hose (2).
Carefully remove fuel level sensor with fuel pump from fuel tank. Tilt components in different directions in so doing.
Carefully withdraw fuel level sensor, tilted against direction of travel, out of tank opening.
Scheme 124
- Replace rubber seal on fuel level sensor.
- Fit rubber seal over fuel level sensor flange.
- Before pressing fuel level sensor into tank opening, detach rubber seal from flange and insert into tank opening.
- Press fuel level sensor into tank opening.
16 12 001 Removing and installing/replacing fuel gauge sensor (left)
| IMPORTANT | Ensure adequate ventilation in the place of work! |
Ensure absolute cleanliness when working on the open fuel tank.
Contaminants in the fuel tank can impair driving operation or may even result in vehicle breakdown!
Necessary preliminary tasks
- Draw off fuel from fuel tank
- Remove rear seat bench
Detach rubber plug above sensor unit on left.
Fold back rubber mat.
Scheme 125
| IMPORTANT | Do not damage gasket. |
Release screws (1) and remove cover.
Scheme 126
Unfasten plug connection (1) and disconnect.
Force off hose with a clamp.
Release hose clamp (2) and carefully detach hose. Do not damage connecting piece when doing so.
Replace hose clip.
Tightening torque, see 16 12 7AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES
Scheme 127
Release screw cap with special tool 16 1 020.
Replace rubber gasket.
Tightening torque, see 16 14 2AZ in FUEL SUPPLY SYSTEM - TIGHTENING TORQUES
Scheme 128
Carefully raise fuel level sensor until sensor flange projects out of sealing area of tank opening.
In so doing, do not pull excessively on connecting piece of fuel return. Risk of breakage!
When installing fuel level sensor, make sure that lug (1) in opening (2) engages fuel tank.
During torque tightening, notch (3) on screw cap can be clearly heard and felt to engage toothed segment (4) on fuel tank.
Scheme 129
| IMPORTANT | Do not bend sensor. |
Carefully pull fuel level sensor upwards until access is gained to suction jet pump connection.
Press retaining lugs (1) inwards.
Carefully pull off connection (2) of suction jet pump towards bottom.
| IMPORTANT | Ensure correct engagement when installing. |
Carefully withdraw fuel level sensor, tilted in direction of travel towards left.
Scheme 130
- Retaining lugs (1) must be completely snapped into place.
- Replace rubber seal on fuel level sensor.
- Fit rubber seal over fuel level sensor flange.
- Before pressing fuel level sensor into tank opening, detach rubber seal from flange and insert into tank opening.
Replace O-ring (1) on fuel level sensor. Before fitting, apply a light coat of engine oil to O-ring.
Check that O-ring is correctly seated when installed.
Connection of suction jet pump is transparent.
Scheme 131
| IMPORTANT | Comply with the following installation instruction without fail. |
Installation
When installing fuel level sensor, comply with the following without fail
Scheme 132
- Insert fuel level sensor flange (1) horizontally into tank opening so that sensor foot (2) is positioned vertically in recess (3) in bottom of fuel tank.
- Press fuel level sensor flange into tank opening.
- Fuel level sensor flange must remain in pressed-in position! When the flange is partially pressed out, the sensor foot (2) is not in the recess (3) in the bottom of the fuel tank.
- Line set (5) must not interlock with sensor arm (4).
This work step is described in removing fuel tank
refer to 16 11 030 REMOVING AND INSTALLING FUEL TANK .
Note. Unlock connections on carbon canister with special tool 16 1 050.
Scheme 133
Disconnect connections (1) to (3).
Scheme 134
Release screws (1).
Remove activated carbon canister downward.
Scheme 135
16 13 015 Removing and installing/replacing tank leakage diagnosis module (DM-TL)
Remove left rear wheel housing trim.
Release screw.
Lift bracket (1) with leakage diagnosis pump (3) and dust filter (4) out of mounting (2).
Scheme 136
Detach plug (1) and filling vent (2) from leakage diagnosis pump (3).
Press together hose retainer (4) and disconnect molded hose (5) from leakage diagnosis pump (3).
Scheme 137
Release screws (1) on rear side of bracket (2) and remove leakage diagnosis pump (3).
Scheme 138
16 14 060 Removing and installing/replacing dust filter for tank leakage diagnosis module (DM-TL)
Remove left rear wheel housing trim.
Press together hose retainer (1) and disconnect molded hose (2) from leakage diagnosis pump (3).
Press together locking lever on rear side of dust filter (4).
Withdraw dust filter (4) towards left from bracket (5).
Disconnect molded hose (2) from dust filter (4).
Scheme 139
16 14 010 Removing and installing/replacing fuel pump
Removing and installing/replacing fuel pump is identical to Removing and installing/replacing fuel gauge sensor (right), refer to 16 12 000 REMOVING AND INSTALLING/REPLACING SENSOR FOR FUEL LEVEL GAUGE (RIGHT) .
Remove left rear wheel housing trim.
Press together hose retainer (1) and disconnect molded hose (2) from leakage diagnosis pump (3).
Press together locking lever on rear side of dust filter (4).
Withdraw dust filter (4) towards left from bracket (5).
Disconnect molded hose (2) from dust filter (4).
Scheme 140
16 14 530 Replacing suction jet pump(s)
Draw off fuel from fuel tank
Remove sensor from left fuel level indicator
Remove sensor from right fuel level indicator
Right Side
Lift line (3) out of holder (4).
Pull lines (1) + (2) to left out of holder (5).
Lines (1) + (2) must noticeably snap into place when fitted in holder (5).
Scheme 141
Feed suction jet pump out of fuel tank and pull out towards top.
Scheme 142
Carefully feed in lines of suction jet pumps, do not kink.
It is absolutely essential to ensure that line set for suction jet pumps is correctly positioned in fuel tank!
Scheme 143
- Suction jet pump in fuel tank, rear left
- Line ends for right side of fuel tank.
- Connection of line set to sensor unit, left.
See also:
• 26 11 000 REMOVING AND INSTALLING COMPLETE PROPELLER SHAFT
• 13 32 051 REPLACING FUEL FILTER
• WHEEL AND TIRES - REPAIR INSTRUCTIONS
• 36 10 300 REMOVING OR INSTALLING FRONT OR REAR WHEEL
• Function Description
• 16 00 005 DRAINING AND FILLING FUEL TANK
• 16 11 130 CHECKING FILLER CAP PRESSURE RELIEF VALVE
• 16 11 030 REMOVING AND INSTALLING FUEL TANK
• 16 12 000 REMOVING AND INSTALLING/REPLACING SENSOR FOR FUEL LEVEL GAUGE (RIGHT)
• 16 12 001 REMOVING AND INSTALLING/REPLACING FUEL GAUGE SENSOR (LEFT)