Volkswagen CJDA Workshop Manual page 393

1.11 Checking return flow rate from fuel
pressure regulating valve -N276-
WARNING
◆ Always read rules for cleanliness and instructions for
working on fuel system
◆ Always follow these rules for cleanliness and instruc-
tions before starting work and while working on the
fuel system.
– Take noise insulation out of injectors.
– Pull off fuel return line -1-.
– Seal open fuel return line connection with a blanking plug
-1-.
– Connect fuel return line -2- to suitable hose -3-.
– Hold end of this hose in a suitable container to measure re-
turn flow rate.
– Start engine and run at idling speed.
● Specification after 5 to 10 seconds: return flow rate = 0 ml
If the specification is not attained, the fuel pressure regulating
valve -N276- is defective.
1.12 Removing and installing fuel pressure
regulating valve -N276-
The fuel pressure regulating valve is located in the fuel rail. The
valves ensure that pressure is constant in the high pressure ac-
cumulator and in the injector lines (fuel high pressure circuit).
If pressure is too high in the fuel high pressure circuit, the regu-
lating valve will open. A small amount of fuel from the high pres-
sure accumulator will thereby make its way back to the fuel tank
via the return line.
If pressure is too low in the fuel high pressure circuit, the regu-
lating valve will close. The valve seals the high pressure side
against the low pressure side in this way.
Workshop Manual for Diesel Engine (2.0 l/36-75 kW_EA 189) 05.2015
⇒ P age
354.
Industriemotoren - Industrial Engines 2009 ▶
1 Repairing diesel direct injection system
3
377