Table of contents: General description ↓ Precautions ↓
General description
The fuel system includes a fuel tank, a high-pressure fuel pump, a fuel filter with a water separator installed in the engine compartment, and supply and return fuel lines and fuel injectors.
The fuel pump rotates at half the crankshaft speed and is driven by a belt from a sprocket on the rear of the camshaft. The pump pumps fuel from the fuel tank through a filter and then distributes it under very high pressure to the injectors through separate lines.
The injectors have mechanical spring-loaded valves that open when the fuel pressure in them exceeds a certain value. The fuel is then sprayed by the nozzle tip into the swirl chambers located above the pistons (direct injection).
The main injection moment is set mechanically by the position of the pump on the suspension bracket. When the engine is running, the injection moment is mechanically adjusted by the fuel pump and depends primarily on the position of the accelerator and the engine speed.
The engine is stopped by the fuel shut-off valve, which interrupts the fuel supply to the fuel pump.
During a cold start, the idle speed can be increased manually using the cold start accelerator cable, which is controlled via a handle on the dashboard in the vehicle's interior.
Note: This Section uses the engine code rather than the displacement to identify the vehicle - for a list of engine codes, see Section 1A.
Precautions
Many of the steps described in this Section involve disconnecting the fuel lines, which may cause fuel leaks.
Warning: When working on the fuel system, avoid contact with diesel fuel on your skin - wear protective clothing and gloves.
Fuel injectors operate at extremely high pressures and the jet of fuel from the tip is capable of piercing the skin. It is recommended that any inspection of the fuel system components be carried out by a specialist in diesel fuel injection systems.
Never allow diesel fuel to come into contact with the cooling system hoses. Hoses that have been contaminated with fuel for a long period of time should be replaced. Diesel fuel injection systems are particularly sensitive to contamination, or the ingress of air and water. When working on the fuel system, keep it clean to prevent dirt from entering the system. Before disconnecting fuel connectors, thoroughly clean the area around them. Store removed components in sealed containers to prevent contamination. Use only thick (lint-free) cloths. Avoid using compressed air when cleaning components that have not been removed.
[Information obtained from this resource AUDImanual]