GF47.30-P-3013KE Fuel Evaporation Control System, Function

GF47.30-P-3013KE Fuel Evaporation Control System, Function
MODEL 203 with ENGINE 271.948 up to Model Year 08 /modification year 07





Model 171
12 Intake manifold
17 Fuel rail
45 Fuel filler neck
55/2 Fuel filter with fuel pressure regulator
71 Check valve
75 Fuel tank
76 Vent valve
77 Activated charcoal canister
77/1 Vent/breather line
M3 Fuel pump
N3/10 ME-SFI [ME] control unit
Y58/1 Purge control valve
A Electrical line
B Fuel pipe
C Purge line

The fuel evaporation control system prevents fuel vapors escaping to atmosphere. The fuel vapors are stored temporarily in the activated charcoal canister (77) for this and burnt in the engine when the conditions are suitable.

1 Model 171
1.1 Air admission to fuel tank
The vent valve (76) opens at a vacuum of approx. 1 up to 16 mbar in the fuel tank (75). Air or fuel vapors are drawn out of the activated charcoal canister into the fuel tank over the activated charcoal canister and aeration/vent line (77/1).
1.2 Fuel tank venting
The vent valve opens at an excess pressure of about 30 to 50 mbar. The fuel vapors flow to the activated charcoal canister where they are stored or they are drawn off into the intake manifold (12) if purging is activated at that moment.
1.3 Refueling
The opening pressure of the vent valve of approx. 30 to 50 mbar is not reached if the cover of the fuel tank has been removed. The vent line to the activated charcoal canister remains closed off. As a result, nozzle is shut off and fuel is not able to reach the activated charcoal canister.





Model 203, 209, 211
12 Intake manifold
17 Fuel rail
45 Fuel filler neck
55/1 Fuel filter with integrated fuel pressure regulator (for models 203, 209)
55/2 Fuel filter with fuel pressure regulator (for model 211)
71 Check valve
72 Float valve
75 Fuel tank
75/1 Expansion reservoir
77 Activated charcoal canister
77/1 Vent/breather line
M3 Fuel pump
N3/10 ME-SFI [ME] control unit
Y58/1 Purge control valve
A Electrical line
B Fuel pipe
C Purge line

2 Model 203, 209, 211
2.1 Air admission to fuel tank
Air is admitted through the activated charcoal canister (77). Air or fuel vapors are drawn out of the activated charcoal canister into the fuel tank (75) over the activated charcoal canister and aeration/vent line(77/1).
2.2 Air release from fuel tank
The fuel tank is vented through the activated charcoal canister. In this case, the fuel vapors flow to the activated charcoal canister where they are stored or they are drawn off into the intake manifold (12) if purging is activated at that moment.
2.3 Refueling
The expansion reservoir (75/1) with float valve (72) is designed to prevent fuel flowing to the activated charcoal canister during refueling (overfilling).

3 Active charcoal purging
When the engine is running, the fuel vapors stored in the activated charcoal canister, are drawn off through the purge control valve (Y58/1) and combusted in the engine.
The check valve (71) in the purge line prevents the charge pressure building up toward the activated charcoal canister.

The purge control valve is actuated by the ME control unit (N3/10) for purging, if:
- Coolant temperature greater than 70 °C
- Engine start greater than 2 minutes previously
- Engine not in the overrun mode
- Engine not in the lambda adaptation phase

The purge quantity is determined by constantly opening and closing the purge control valve with on periods of varying lengths.
The idle speed control prevents changes in engine speed resulting from purging. A richer or leaner fuel-air mixture is produced in line with the charge of the activated charcoal canister with fuel vapors.