Daewoo KORANDO Service Manual page 694

Function of the Fuel Pressure Regulator
The fuel pressure regulator maintains the fuel pressure in the
fuel line with the pressure of 3.2 bars to 3.8 bars according to
the intake manifold pressure. This operating pressure cannot
be changed, and the fuel injection volume will be only
determined by the injection time. Over supplied fuel returns to
the fuel tank through the return line.
<Operating at full load>
There is no negative pressure applied to the spring chamber(9)
during the full load, and it is separated from the fuel chamber(8)
by the diaphragm(5).
When the fuel pressure goes up, the diaphragm forces the
compression spring(6) in the direction of compression . At this
moment, the valve(3) sticks to the diaphragm by the fuel
pressure, and the fuel return line(2) opens. The fuel over
supplied returns to the fuel tank through the return line.
The pressure difference between the fuel pressure and the
intake manifold is about 3.8 bars during the full load.
<Operating at Idle and partial load>
The spring chamber(9) is connected to the intake manifold
with the vacuum hose at the intake pipe connection(7). The
negative pressure generated in the intake manifold activates
the diaphragm, and thus the fuel pressure gets reduced to the
rate of the operating extent of the diaphragm by the intake
manifold's negative pressure.
Consequently, the fuel pressure in the fuel distributor changes
by the intake manifold's negative pressure, and the injector's
fuel pressure gets reduced independently to the throttle valve's
position. Thus, the fuel injection volume can only be determined
according to the injector's injecting duration.
2. Fuel return line
3. Valve
5. Diaphragm
6. Compression Spring
8. Fuel chamber
9. Spring Chamber
1. Fuel pressure Regulator
2. Intake Manifold
3. Fuel return(to fuel tank)
4. Fuel supply(form fuel pump)
5. Fuel pressure(approx. 3.8 bars)
6. Intake Manifold Negative Pressure(0 bar)
M161 ENGINE CONTROLS 1F2-47
A. Valves Closed
B. Valves Opened