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

MODEL 216.3, 221.0/1 with ENGINE 157.9 with CODE (494) USA version

MODEL 216.3, 221.0/1 with ENGINE 278.9 with CODE (494) USA version

Fig 1: On-Board Refueling Vapor Recovery - Schematic Diagram

Courtesy of MERCEDES-BENZ USA

Schematic representation

On-board refueling vapor recovery, general points

The legislator requires, that the refueling gases in the vehicle are collected (ORVR = Onboard Refueling Vapor Recovery).

Fuel and refueling vapors must be separated in order to prevent fuel from flowing into the activated charcoal canister due to inappropriate refueling or a defective nozzle.

Function sequence for on-board refueling vapor recovery

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 in the fuel tank.

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

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

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

The aeration/vent valves can also close briefly if there is sudden braking or acceleration, or when 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.

Overview of system components for gasoline injection and ignition system with direct injection

GF07.70-P-9998MMB