Table of contents: Conditions for working with the…🠇 Security measures 🠇
In a diesel engine, fuel and air are supplied separately. First, air is sucked into the cylinder, then it is compressed and only after that, at the end of the compression stroke, fuel is injected.
Self-ignition of fuel is accompanied by a sharp, sudden increase in pressure in the cylinder - this explains the usually noisy, "rough" operation of a diesel engine. For smoother fuel ignition, a two-stage injection and a sophisticated electronic control system are used.
A characteristic feature of diesel engines is the presence of solid particles—soot—in their exhaust gases. For proper combustion of diesel fuel, a significant, even excessive, amount of air is required.
Injectors are used to inject and atomize fuel, as well as to distribute its particles throughout the combustion chamber. A high compression ratio requires the use of appropriate fuel pumps – the pressure in the injector nozzle must reach several hundred bar. All this complicates and significantly increases the cost of the fuel supply system and, accordingly, the diesel engine itself.
Fuel is supplied to the injectors by a high-pressure fuel pump (HPFP).
To reduce the amount of harmful substances contained in exhaust gases, an oxidation catalytic converter is installed on vehicles with diesel engines. For this purpose, the exhaust gas recirculation system is also used, when part of the exhaust gases is mixed with fresh air entering the engine, resulting in a reduction in the oxygen content that will be burned in the engine cylinders. As a result, the combustion temperature of the combustible mixture decreases and, consequently, the amount of nitrogen oxides formed decreases.
With direct injection, fuel enters the combustion chamber directly.
The air flow entering the engine is swirled in a spiral in the intake ports, which improves the combustion process in the engine cylinders.
Before entering the high-pressure fuel pump, the fuel passes through a fuel filter, where water is separated from the fuel. This water must be drained periodically.
The fuel pump is driven by a toothed belt. Its internal moving parts are lubricated with diesel fuel.
The vehicle's fuel system consists of a fuel tank, fuel lines, fuel filter, high-pressure fuel pump and injectors.
Caution! Do not allow diesel fuel to come into contact with the cooling system hoses. Hoses that have been exposed to diesel fuel for a long time must be replaced. The diesel engine fuel system is particularly sensitive to contamination, so ensure maximum cleanliness when working on the fuel system. Before disconnecting the fuel lines, thoroughly clean them from dirt. When removing system components, cover open areas with a lint-free cloth. Do not use compressed air to clean engine mounted system components. When checking the operation of the injectors, never place your hands or any part of your body under the stream of fuel coming out of the injector. Fuel comes out of the injector under high pressure and can penetrate the skin. Use goggles to protect your eyes from fuel getting into them. If fuel comes into contact with your skin, rinse with plenty of water. Install only clean power supply system components. Remove spare parts from their packaging immediately before installation.
Caution! Use goggles to protect your eyes from fuel. If fuel comes into contact with your skin, rinse with plenty of water. Install only clean power supply system components. Remove spare parts from their packaging immediately before installation.
Conditions for working with the BOSCH power supply system
Caution! Adding additives such as fuel system cleaner to diesel fuel is prohibited.
Security measures
All work on the fuel injection system must be carried out in accordance with established requirements and regulations that ensure the prevention of accidents and protection of the environment.
Work must be carried out by specially trained personnel who are aware of safety recommendations and measures to be taken.
Considering the very high pressures (1350 bar) that are created in the fuel system, follow these recommendations:
- smoking is prohibited in the immediate vicinity of the high-pressure hydraulic circuit during work;
- it is prohibited to work near open flames or sparking objects;
- it is prohibited to carry out work on the high-pressure hydraulic fuel circuit while the engine is running;
- after stopping the engine, use the DIAG 2000 device to ensure that the pressure in the fuel distribution line has dropped to atmospheric pressure before carrying out any work. This process may take several minutes.
With the engine running:
- always stay out of the reach of any fuel jet that may accidentally escape from the nozzle, as this could cause serious injury;
- keep hands away from leaks in the high-pressure fuel circuit.
The work area must be clean and away from other vehicles. Parts removed during repairs must be stored in places protected from dust.
Before working on the fuel system, clean the fuel system parts and components:
- fuel filter;
- high-pressure fuel pump;
- fuel distributor (Common Rail);
Caution! Before performing any work on the engine, read the memory of the injection system control unit.
- high-pressure fuel lines;
- injectors.
Immediately after removal, plug the high-pressure pipes to prevent dirt from entering the high-pressure circuit.
[Original text is located at: PEUGEOTBOOK]
It is prohibited to disconnect or remove the following components from the high-pressure fuel pump:
- high-pressure fuel pump 3rd piston switch;
- sealing sleeve on the pump drive shaft side;
- high pressure fuel outlet nipple.
It is prohibited to disconnect the high pressure sensor from the end of the fuel distribution line.
Caution! Do not clean carbon deposits from the injector nozzle tip, nor do you use diesel fuel or ultrasound to clean it. All work with high-pressure fuel lines must always be accompanied by their mandatory replacement.
It is prohibited to disconnect or remove the following components from the injector:
- spray;
- solenoid valve winding;
- turn or loosen hex nuts.
When replacing the fuel system control unit, it is necessary to initialize the engine blocking system.
To perform initialization, the following conditions must be met:
- have an access code to the analog module (recorded on the client's confidential card);
- have a new fuel system control unit and diagnostic tool;
- initialize the engine control unit;
- carry out coding of the engine control unit.
Caution! Interchanging fuel injection system control units on two vehicles will prevent the engine from starting.