On-Board Refueling Vapor Recovery Function - GF47.10-P-3004MMK
Engine 276.8 in model 217, 222
with code 494 (US version)
Schematic representation of the fuel tank (up to model year 2016)
Schematic representation of the fuel tank (except model 222.163 as of model year 2016)
Schematic representation of fuel tank (for engine 222.163)
On-board refueling vapor recovery, general points
The law requires, that the refueling gases in the vehicle are collected (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 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 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 aeration/vent valves and aeration/vent lines to the activated charcoal canister, where they are stored.
The fueling, pressure limitation and vent valve also prevents overfilling by closing off the aeration and 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.
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