The fuel system uses electro-hydraulic injectors, the operation of which is controlled by an electronic control module.
Fuel under high pressure is supplied to the injector from the rail.
The solenoid valve located in the upper part of the injector actuates the needle, which delivers the required amount of fuel through the nozzle into each cylinder.
Multiple fuel injection is carried out on command from the electronic module (ECM), which controls the operation of the injector solenoid valves.
The clearances in the injector nozzle holes are too small, and the ingress of any contaminants leads to clogging of the injector.
Therefore it is important to remove dirt around all fuel system fittings before servicing it.
The high-pressure line fitting contains a slot filter that breaks up small dirt particles that have entered the fuel system.
It uses high-frequency fuel pressure oscillations to break down most particles to a size corresponding to the injector flow section.
All injectors are connected to a common low-pressure line return circuit.
All excess fuel from the injectors, the rail and the fuel pump is returned to the fuel tank through the low-pressure line.
A low-pressure non-return valve is installed in the low-pressure line and prevents fuel from returning to the injectors through this circuit.
The return lines are fitted at each injector with pressure fittings with spring-retainer clips.
If an injector is faulty or partially faulty, the engine will run unevenly, consume more fuel, and the engine will «shake».
A fuel leak through the return line caused by a fault in any injector can be checked as follows.
Disconnect the fuel return line from each injector.
Press the retainer securing the return line union.
Disconnect the return line from the injector.
Connect separate drain hoses included in the injector tightness test kit (catalogue number 4918899).
If this kit is not available, hoses of a suitable size can be used.
Lower all four hoses into separate measuring containers.
Start the engine and measure the amount of fuel collected in one minute.
Compare the results for each injector.
The maximum fuel flow for each injector must be 20 ml/min.
Removing the injectors
The injectors should not be removed without necessity!
Disconnect the negative battery terminal.
Clean the injector area with compressed air or steam.
Press the retainer and disconnect the wiring connector from the injector.
Press the retainer securing the return line union to the injector.
Disconnect the line from the injector.
Unscrew the nut securing the high-pressure line to the rail.
Holding the injector union to prevent it from turning, unscrew the nut securing the high-pressure line to the injector.
Remove the line.
Unscrew the bolt securing the injector holder and remove it.
Remove the injector holder.
Remove the injector.
Replace the copper sealing ring of the injector body.
To remove the injector, break it free slightly and turn it by hand, carefully rocking it in various directions.
If additional force is required to remove the injector, a tool (catalogue number 4919661) can be used.
Carefully insert the tool into the recess of the valve cover.
At the same time, make sure that the two supports of the puller are located under the injector collar.
Using the slide hammer, apply a smooth vertical force to the body.
After removing the injector, fit a protective cap on the injector nozzle and mark the injector.
The injector body and nozzle should be cleaned in an ultrasonic bath using a safe water-based cleaning agent.
Remove the protective cap from the injector nozzle.
Lower the injector vertically into the ultrasonic bath.
The high-pressure line connectors and electrical connectors must be protected from the ingress of cleaning agent.
Check the injector tip for the absence of carbon deposits and corrosion.
Check the electrical connector for the absence of damage.
The resistance at the contacts must be within 0.215–0.295 Ω.
Record the adjustment code and installation location of each injector.
The adjustment code is a seven-character alphanumeric code applied to the upper part of the injector.
Before installing the injector, apply an anti-seize compound (catalogue number 3824879) or its equivalent to the points where the injector contacts the cylinder head.
During installation, use a copper sealing washer.
The sealing washer must be 1.5±0.06 mm thick.
Only one copper sealing washer should be fitted to the injector.
The valve cover seal should be lightly lubricated to facilitate injector installation.
A loose tightening of the supply line when connecting it to the injector will facilitate precise injector installation.
Fit the bolt to secure the clamp and tighten the bolt. Tightening torque: 15 N·m.
Bleed the fuel system and start the engine.
Check the tightness of all connections.
Materials used and recommendations
When servicing the injectors, use the tightness test kit (catalogue number 4918899) or hoses of a suitable size and clean measuring containers. To remove the injector, use the puller (catalogue number 4919661) if necessary. Before installation, apply an anti-seize compound (catalogue number 3824879) or its equivalent to the points where the injector contacts the cylinder head. Use only one copper sealing washer 1.5±0.06 mm thick per injector.
To clean the injector body and nozzle, use an ultrasonic bath with a safe water-based cleaning agent. Protect the high-pressure line connectors and electrical connectors from the ingress of cleaning agent. After installing the injectors, bleed the fuel system, start the engine and check the tightness of all connections. Maintain cleanliness: contaminants in the nozzle holes are unacceptable, so before servicing, thoroughly clean the area around the fittings with compressed air or steam.