On-Board Refueling Vapor Recovery Function - GF47.10-P-3004MNL
Engine 176.9, 177.9 in model 217
with code 494 (US version)
Engine 176.9, 177.9 in model 222
with code 494 (US version)
Engine 177.9 in model 290
up to model year 2021
with code 494 (US version)
Schematic diagram
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 of the nozzle is therefore accelerated in the filler neck and the air around the nozzle is sucked into 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 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.
| Overview of system components for gasoline injection and ignition system with direct injection | GF07.70-P-9998MNL |