On-board refueling vapor recovery function - GF47.10-P-3004AMG

MODEL 164, 251 with ENGINE 156.980 with CODE (494) USA version 

MODEL 209 with ENGINE 156.982 with CODE (494) USA version 

MODEL 211, 219 with ENGINE 156.983 with CODE (494) USA version 

MODEL 216, 221 with ENGINE 156.984 with CODE (494) USA version 

Fig 1: Identifying On-Board Refueling Vapor Recovery Function Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The legislator demands: 

• Refueling vapors must be recovered (ORVR = O  nboard R  efueling V  apor R  ecovery)
• Fuel and refueling gases must be separated in order to prevent fuel from flowing into the activated charcoal canister due to inappropriate refueling or a defective nozzle.

Thanks to its shape, the fuel filler neck functions as a suction jet pump. The fuel out of the nozzle accelerates through this in the filler neck and air is suctioned around the nozzle.

As a result of this air intake (in the fuel tank) around the nozzle, refueling vapors are not able to rise up at the fuel filler neck and escape into the atmosphere.

The refueling vapors flow though the vent lines to the expansion reservoir and then on to the activated charcoal canister, where they are stored.

When the canister is regenerated (purge control valve actuated), refueling vapors are drawn with the fuel gases out of the activated charcoal canister by the engine via the purge line and burnt.

If fuel reaches the safety valve located high up in the expansion reservoir, the safety valve seals off the vent line to the activated charcoal canister and thus prevents fuel from entering the activated charcoal canister.

The safety valve may also close briefly in the event of sharp braking, accelerating or cornering.

Stop refueling when the nozzle is switched off and the fuel tank is full! On no account overfill the fuel tank by switching on the refueling nozzle being several times.