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Fuel system
The fuel system is demand-controlled on the high and low-pres-
sure sides. On the low-pressure side, the engine control unit regu-
lates the fuel pump control unit J538 and with it the delivery rate
of the fuel pump in the fuel tank.
On the high pressure side, the engine control unit regulates the
fuel metering valve N290 directly at the high-pressure pump.
To monitor the pressure levels in the system, two fuel pressure
senders send their respective signals to the engine control unit.
The central element of the fuel system is a demand-controlled
single-piston high-pressure pump. This generation III fuel pump
by Hitachi is driven by a three-lobe cam seated on the exhaust
camshaft.
The system with a maximum pressure of 120 bar.
The pressure-limiting valve in the pump opens at a pressure of
approx. 145 bar.
451_003
Reference
To learn more about the functional principle and control concept of the high-pressure fuel pump, refer to Self-Study
Programme 432 "Audi 1.4l TFSI engine".
Note
Caution: danger of injury. The system operates at very high pressures. To open the high-pressure side, always follow the
instructions given in the Workshop Manual.
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