Fuel Pressure Sensor: Service and Repair
WM 240919 Removing and installing high-pressure sensor (rail pressure sensor) on DFI engines
Tools
Technical values
Preliminary work
1. Remove engine compartment covers at the plenum panel at the middle and left. For details, see -> 700219 Removing and installing front trim (engine compartment) - section on "Removing" Service and Repair
2. Remove fuses on both fuel pumps from the central electrical system's slots or disconnect the battery. This prevents the fuel pumps from starting when the door is opened.
Information
Component overview
DFI injection system, 3.6 l
Removing high-pressure sensor (rail pressure sensor)
DANGER
Danger of poisoning from fuels.
-> Gasoline is toxic.
-> Inhaling vapours can cause irritation of the mucous membranes and eyes.
-> It can be carcinogenic. It represents a serious risk to health when inhaled, touched or swallowed over longer periods.
-> Only work on the fuel system in well-ventilated rooms.
-> Wear protective gloves that are fuel-resistant.
-> Wear a breathing mask with active charcoal filter; do not breathe in any fuel vapours.
-> Ensure that there is adequate ventilation and extract all fuel vapours.
-> Before opening the fuel lines or fuel hoses, relieve the fuel pressure.
-> Collect escaping fuel, absorb it if necessary with a suitable binding material and dispose of properly.
-> Pay attention to cleanliness when working on the fuel system.
DANGER
Danger of fire from fuel.
-> Keep clear of ignition sources.
-> Do not smoke.
-> Disconnect battery.
-> Danger of fire due to naked flames and sparks, e.g. during welding or grinding work.
-> Danger of fire due to escaping fuel, e.g. on hot engine components or due to electrostatic charge. Allow engine to cool down.
-> Secure the vehicle, e.g. with a warning sign.
-> Change any clothing soaked with fuel immediately.
-> In case of fire, use CO2 or dry powder fire extinguishers.
CAUTION
Dirt on injection system components (intake manifold injection and direct fuel injection system)
- Material damage
- Rough-running engine
- Bad exhaust emissions
-> Thoroughly clean connection points and adjacent areas before loosening them. If the engine is very dirty, wash it before starting disassembly work.
-> Lay removed parts on a clean surface and cover them. Do not use fibre-shedding cloths.
-> Carefully cover components or seal them if repair work will not be carried out immediately. Place rubber caps on connections. Seal intake openings with film or adhesive tape.
-> Only install clean parts. Do not take spare parts out of the packaging until just before installation.
-> Never use compressed air when the system is open. Do not move the vehicle.
CAUTION
Danger of fire from leaking high-pressure lines.
- Fuel can leak out if high-pressure lines are bent or damaged.
- Fuel can leak out if threaded joints are not fitted correctly.
- Fuel can leak out if the tightening specifications are not observed.
-> Never bend high-pressure lines.
-> The high-pressure distribution pipe (rail) or other fuel feed components in the high-pressure area must always be completely removed.
-> Perform a visual inspection to ensure that connection points are undamaged and perfectly clean.
-> Check that threaded joints at connection points are not seized up or corroded. Make sure the thread is not damaged.
-> Fit union nuts on all connection points by hand before screwing in screws or bolts.
-> Pay attention to cleanliness. Remove dirt on the ball/conical joints.
-> Check or inspect connection points for leaks following assembly.
Information
- The ignition must be switched off when working on the fuel system.
- Absorb any escaping fuel using a suitable binding material or a cloth.
- Cloths which have absorbed fuel must be disposed of according to the applicable national laws.
- The fuel system must be depressurised before starting work on it.
- Only work on the fuel system in well-ventilated rooms.
- Any seals which have been removed must always be replaced.
1. Remove cable plug for high-pressure sensor -3-.
View of threaded connections for high-pressure system
2. Place a cloth under the high-pressure sensor and remove the high-pressure sensor slowly using a long socket (e.g. Hazet 900 Lg socket-wrench insert Nr.188 or a similar tool). Relieve the fuel pressure by slowly opening the high-pressure sensor.
3. Visually check the thread and sealing ball to make sure they are not damaged.
Installing high-pressure sensor (rail pressure sensor)
1. Visually check the thread and sealing ball to make sure they are not damaged.
2. It must be possible to turn the high-pressure sensor slightly by hand. Lightly lubricate the high-pressure sensor with engine oil.
3. Bolt on the high-pressure sensor using a long socket (e.g. Hazet 900 Lg socket-wrench insert Nr.188 or a similar tool) -3-. => Tightening torque: 22 Nm (16 ftlb.)
View of threaded connections for high-pressure system
4. Connect cable plug for high-pressure sensor.
5. Check high pressure distribution pipe for leaks. Following a test drive, visually inspect the high-pressure sensor with a mirror and lamp at idle speed.
Subsequent work
1. Insert fuses on both fuel pumps into the central electrical system's slots or connect the battery.
2. Fit engine compartment covers at the plenum panel in the middle. For details, see -> 700219 Removing and installing front trim (engine compartment) - section on "Installing" Service and Repair