INTRODUCTION - FUEL TANK AND PIPES

1.3 Multijet

This fuel injection system uses an electronically-controlled high injection pressure and a fuel delivery method produced by one main injection and one or more pilot injections (depending on the engine operating conditions), electronically-controlled by the injection control unit via the injector; this system is capable of carrying out up to five injections (depending on the actual engine operating conditions).

Pressure level is one of the basic parameters for optimising fuel consumption and exhaust fume levels.

Controlling the ignition by means of several pilot injections makes it possible to preheat the combustion chamber to avoid the pressure peak caused by rapid combustion and ensure smoother running with a further reduction in emissions.

Injection pressure adjustment is made possible by the construction features of the system, which is equipped with a separate pressure pump, pressure regulator, pressure sensor and injectors, all managed by a control unit. In this way, injection pressure is independent of engine rotation speed.

The main features of the fuel supply system are as follows:

• high injection pressure (up to 1400 bar);
• injection pressure that can be modulated from 150 to 1400 bar under all engine operating conditions;
• introduction of fuel up to 50 mm³/cycle within a speed range of 100 to 5200 rpm;
• precise injection control in terms of advance and duration;
• one or two pilot injections before TDC, managed on the basis of rpm and engine load, which allow the pressure in the combustion chamber to be distributed more evenly with a reduction in noise levels.

The fuel system is divided into a low pressure circuit and a high pressure circuit.

The low pressure circuit consists of:

• an auxiliary pump immersed in the tank;
• the fuel filter with an internal cartridge;
• the fuel return manifold pipe;
• the connecting pipes.

The high pressure circuit consists of:

• the pressure pump;
• the single fuel manifold pipe with built in pressure regulator and pressure sensor;
• the injectors;
• the connecting pipes.

1. Fuel tank

2. Fuel filler pipe

3. Reflux pipe

4. Fuel filter

5. Water in fuel filter sensor

6. Pressure pump

7. High pressure pipes

8. Single fuel manifold pipe

9. Injectors

10. Pipe from injectors to fuel return manifold pipe

11. Fuel return manifold pipe

12. Pressure regulator

13. Fuel pressure sensor

14. Fuel temperature sensor

15. Fuel heater

1.2 8v

The fuel system is returnless, i.e. with a single pipe connecting fuel tank and engine. The return pipe, filter and pressure regulator have therefore been eliminated. The filter and pressure regulator are built into the pump assembly.

This makes it possible to:

• minimise the possibility of the vehicle catching fire in case of an accident
• reduce fuel vapour emissions into the atmosphere.

The fuel tank is located in front of the rear axle. It is made out of plastic with high mechanical strength.

The fuel supply system components are illustrated in the diagram below.

1. Fuel tank

2. Submerged pump assembly

3. Fuel filler pipe

4. Fuel manifold

5. Injectors

See descriptions 1056 PETROL INJECTION SYSTEM