Evaporative emission control system function - GF47.30-P-3013KE
MODEL 203 with ENGINE 271.921
MODEL 203, 209 with ENGINE 271.940
MODEL 211 with ENGINE 271.941
MODEL 171 with ENGINE 271.944
MODEL 203 with ENGINE 271.946
MODEL 203 with ENGINE 271.948
MODEL 209 with ENGINE 271.955
MODEL 211 with ENGINE 271.956
The evaporative emission 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.
- Model 171
- 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).
- 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.
- 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.
- Air admission to fuel tank
- Models 203, 209, 211
- 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).
- 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.
- Refueling
The expansion reservoir (75/1) with float valve (72) is designed to prevent fuel flowing to the activated charcoal canister during refueling (overfilling).
- Air admission to fuel tank
- 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 > 70°C
- Engine start before >2 minutes
- Engine not in the overrun mode
- Engine not in 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.
| Component description for a coolant temperature sensor | B11/4 | GF07.04-P-6040KE | ||
| Component description for a the ME-SFI [ME] control unit | N3/10 | GF07.61-P-6000KE | ||
| Component description for the fuel tank | 75 | Model 171 | GF47.10-P-2000VE | |
| 75 | Model 203, 209 | GF47.10-P-2000PE | ||
| 75 | Model 211 | GF47.10-P-2000TE | ||
| Component description for the activated charcoal canister | 77 | GF47.30-P-2010KE | ||
| Component description for a purge control valve | Y58/1 | GF47.30-P-2020KE | ||