On-Board Refueling Vapor Recovery Function - GF47.10-P-3004MNH

Model 463 with engine 176.9, 177.9 

as of model year 2019 

with code ZU8 (National version for USA) 

Courtesy of MERCEDES-BENZ USA

On-board refueling vapor recovery, general points 

The lawmaker requires that the refueling gases are captured in the vehicle. Fuel and refueling vapors must be separated in order to prevent fuel from flowing into the activated charcoal canister due to any inappropriate refueling or a defective nozzle.

Function sequence for on-board refueling vapor recovery 

Owing to its form, the filler neck functions as a suction jet pump. The fuel flow out from the pump nozzle is accelerated in this way in the filler neck and air is sucked in around the nozzle in the fuel tank.

As a result of this air intake. the refueling vapor are not able to gather at the filler neck and are able to escape.

The fuel vapors flow through the vent/bleed valves and vent/bleed lines to the activated charcoal canister, where they are stored. The fueling, pressure limitation and vent valve also prevents overfilling by closing off the vent and bleed line.

Rollover valves are integrated at the top of the vent/bleed valves. If fuel gets into vent/bleed valves, the rollover valves close off the vent/bleed lines to the activated charcoal canister, thus preventing fuel from flowing into the activated charcoal canister.

The vent and bleed valves may also briefly close in the case of severe braking, acceleration or cornering.

When purging is enabled, the fuel vapors are drawn off through the purge line by the engine, and burnt together with the fuel gases from the activated charcoal canister.