Fuel Filter: Description and Operation

GF47.20-P-2110VC Fuel Filter With Fuel Pressure Regulator, Component Description
- ENGINE 272.920 /940 /941 in MODEL 203 up to Model Year 8
- ENGINE 272.940 in MODEL 209
- ENGINE 272.966, 273.965 in MODEL 230 up to Model Year 8





Shown on model 203, 209
48 Fuel pressure regulator vent line
55/2 Fuel filter with fuel pressure regulator
89/1 Left closing plate
B4/3 Fuel tank pressure sensor (United States of America)
A Fuel pressure line to engine (controlled fuel pressure)





55/2 Fuel filter with fuel pressure regulator
55/3 Valve
55/5 Diaphragm
55/6 Compression spring
55/9 Filter element
55/40 Diaphragm pressure regulator
A Feed from fuel pump
B Fuel return flow to fuel tank
C Fuel pressure connection to engine
D Diaphragm pressure regulator vent line

Location
Model 203, 209: The fuel filter with integrated fuel pressure regulator is located to the rear of the left-hand chamber of the fuel tank.

Design
The fuel filter consists of a sheet metal casing with an integrated filter element (55/9). The fuel flows through this from the outside to the inside. As a result any impurities are trapped.

Model 230: The fuel filter with integrated fuel pressure regulator is located under the fuel tank at the frame floor assembly.

Function
The fuel pressure regulator controls the fuel pressure of around 3.8 bar (system pressure) via the fuel return volume
If the set fuel pressure is exceeded, the diaphragm is pushed against the push spring and the valve attached to the diaphragm opens the passage for the fuel return.
If the set fuel pressure is below the limit, the valve is closed again by means of the push spring.





Fuel pressure as a function of the fuel pump delivery
A Fuel pressure in bar
B Fuel pump delivery volume in liters per hour

A greatly varying fuel pump delivery (e.g. 20 or 140 liters per hour) does not have any great effect on the fuel pressure.