Fuel evaporation control system, function - GF47.30-P-3013SM
MODELS 203 with ENGINE 113.988
MODELS 209 with ENGINE 113.987
MODELS 215 with ENGINE 113.986
MODELS 220 with ENGINE 113.986
Model 171
The evaporative emission control system prevents fuel vapors escaping to atmosphere. This is done by temporarily storing the fuel vapors in the activated charcoal canister (77).
When the engine is running, the fuel vapors stored in the activated charcoal canister are checked and suctioned off over the purge control valve (Y58/1) and burnt in the engine.
Purging of the activated charcoal canister takes place at:
- coolant temperature > 70°C
- >2 minutes after the engine has started
- Engine not in the overrun mode
- Engine not in the lambda adaptation phase
To control the purge quantity the purge control valve (Y58/1) is actuated by the ME control unit (N3/10) means of a PWM signal and pulsed.
The purge quantity is determined by continuously opening and closing the purge control valve with on-periods of varying durations.
A richer or leaner fuel-air mixture is produced in line with the charge of the activated charcoal canister with fuel vapors.
The idle speed control ensures that there are no changes in the engine speed at idle speed due to regeneration.
- Models 203, 209
- Refueling
An expansion reservoir (92) with safety valve (93) should prevent fuel flowing to the activated charcoal canister during refueling (overfilling).
- Air admission to fuel tank
Air is admitted through the activated charcoal canister. This is done through the activated charcoal canister, whereby air is drawn out of aeration/vent line for the activated charcoal canister (77/1) or fuel vapors are sucked from the activated charcoal canister into the fuel tank (75).
- Fuel tank venting
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 drawn into the intake manifold in case of simultaneous regeneration.
- Refueling
- Models 171, 215, 220
- Refueling
The release pressure of the vent valve (76) of around 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
The vent valve opens at a vacuum of around 1 to 16 mbar in the fuel tank. This is done through the activated charcoal canister, whereby air is drawn out of the vent line and / or fuel vapors from the activated charcoal canister into the fuel tank.
- Fuel tank venting
The vent valve opens at an excess pressure of around 30 to 50 mbar.
- Refueling
The fuel vapors flow to the activated charcoal canister, where they are stored or drawn into the intake manifold in case of simultaneous regeneration.
The aeration/vent line for the activated charcoal canister is closed by the activated charcoal filter shutoff valve (Y58/4) upon actuation by the ME control unit.
The additional vent valve (76/1) prevents vacuum reaching from the intake manifold over the activated charcoal canister to the fuel tank when purging is released. This closes the valve just as soon as a membrane has vacuum from the activated charcoal canister applied to it. If an overpressure or vacuum acts upon another connection on the valve then it opens immediately. This means that the aeration / venting of the fuel tank over standard vent valve (76) is still unrestricted.
Pay attention to installation position of vent valve (76/1).
Check aeration at activated charcoal canister for dirt (e.g. dust, spider webs).
| ME-SFI [ME] control unit, component description | N3/10 | GF07.61-P-6000SM | ||
| Fuel tank - Description of components | 75 | Model 171 | GF47.10-P-2000VS | |
| 75 | Models 203, 209 | GF47.10-P-2000PS | ||
| 75 | Model 215, 220 | GF47.10-P-2000MS | ||
| Component description for the fuel filter with integrated fuel pressure regulator | 55/1 | Model 215, 220 | GF47.20-P-2101SM | |
| Component description for the fuel filter with fuel pressure regulator | 55/2 | Models 171, 203, 209 | GF47.20-P-2110SM | |
| Component description for the activated charcoal canister | 77 | GF47.30-P-2010SM | ||
| Component description for the purge control valve | Y58/1 | GF47.30-P-2020SM | ||