Self-Study Programme 334 Fuel system in FSI engines.pdf

(1625 KB) Pobierz
SSP 334 - The fuel system in FSI engines
Service Training
Self-Study Programme 334
The fuel system in FSI engines
Design and function
332218589.015.png 332218589.016.png 332218589.017.png 332218589.018.png 332218589.001.png 332218589.002.png 332218589.003.png
All FSI engines with a power output of over 66 kW are fitted with an improved fuel system.
In this fuel system:
- the high pressure fuel pump and the fuel rail
receive a special coating that makes them
corrosion resistant to fuels with an ethanol content
of up to 10 percent.
- there is no more leakage line on the high pressure
fuel pump.
- the pressure limiting valve leakage line on the fuel
rail follows the shortest route to the low pressure
fuel system upstream of the high pressure fuel
pump.
- high pressure fuel pump activation has been
changed.
S334_074
This self-study programme describes the design and function of the improved fuel system using the example of the
2.0 ltr 110 kW FSI engine.
NEW
Important
Note
This self-study programme shows the design and
function of new developments.
The contents will not be updated.
Please always refer to the relevant Service Literature
for all inspection, adjustment and repair instructions.
2
332218589.004.png 332218589.005.png
Contents
General overview of the fuel system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Demand-controlled fuel system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Fuel system components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Fuel pump control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electric fuel pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
High pressure fuel pump with fuel pressure regulating valve . . . . . . . . . . . . 8
Fuel pressure sender for lower pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Fuel pressure sender, high pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
High pressure injectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Pressure limiting valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Connecting piece with restrictor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Test your knowledge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3
332218589.006.png 332218589.007.png
General overview of the fuel system
Demand-controlled fuel system
The demand-controlled fuel system consists of a low pressure and a high pressure fuel system.
It has the advantage that both the electric fuel pump and the high pressure fuel pump convey only as much fuel as
the engine needs at a particular time. This reduces the electrical and mechanical drive power of the fuel pump and
saves fuel.
Low pressure fuel system
The low pressure fuel system has a fuel pressure in
normal mode ranging from 0.5 to 5 bar.
The pressure is raised to 6.5 bar for hot and cold
starts.
Door contact switch for
fuel pump supply
Onboard supply control
unit J519,
power supply for fuel
pump supply
This pressure increase produces a higher initial
pressure in the high pressure fuel system for cold
starts. It achieves better mixture preparation and a
quicker start.
Battery
The pressure increase also prevents the formation of
vapour bubbles in the high pressure fuel pump for hot
starts.
Motronic control
unit J220
Fuel pump
control unit J538
Return line
Restrictor
It consists of:
- Fuel pump control unit J538
-Fuel tank
- Electric fuel pump G6
- Fuel filter with pressure limiting valve
(opens at approx. 6.8 bar)
- Fuel pressure sender for lower pressure G410
Fuel filter with
pressure limiting valve
Electric
fuel pump G6
Fuel pressure sender
for lower pressure
G410
Colour codes/Legend
No pressure
Fuel tank
Low pressure fuel system
Low pressure
High pressure
High pressure fuel system
4
332218589.008.png 332218589.009.png 332218589.010.png 332218589.011.png
High pressure fuel system
The fuel pressure in the high pressure fuel system
ranges from 30 to 110 bar. The pressure range may
vary from engine to engine.
Fuel pressure sender, high
pressure G247
Pressure limiting valve
Important: Be careful when opening the
high pressure fuel system. Please observe
the instructions in the workshop manuals.
Leakage line
It consists of:
High pressure
fuel pump
- High pressure fuel pump
(corrosion resistant to fuels with an ethanol content
of 10%)
- Fuel pressure regulating valve N276
- Fuel rail
(corrosion resistant to fuels with an ethanol content
of 10%)
- Pressure limiting valve
(opens at approx. 120 bar)
- Fuel pressure sender, high pressure G247
- High pressure injectors N30-N33
Fuel pressure
regulating valve N276
Fuel rail
High pressure injectors
N30-N33
S334_032
5
332218589.012.png 332218589.013.png 332218589.014.png

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika:

Zgłoś jeśli naruszono regulamin