Refueling Vapor Recovery System: Description and Operation

GF47.10-P-3004MIS On-board Refueling Vapor Recovery Function
MODEL 216.3, 221.0 /1 with ENGINE 273.9
- with CODE (494) USA version as of 2009 /YoM 08





Schematic diagram of fuel tank aeration and ventilation
1 Activated charcoal canister chamber 1
2 Activated charcoal canister chamber 2
3 Activated charcoal canister chamber 3
45 Fuel filler neck
45/1 Refueling ventilation
45/2 Float with flap
58 Fluid reservoir
75 Fuel tank
75/1 Safety valve (rollover valve)
75/2 Fuel retention valve
77 Activated charcoal canister
B4/3 Fuel tank pressure sensor
Y58/1 Purge control valve
Y58/4 Activated charcoal filter shutoff valve
A Air admission line and vent line
B Purge line

On-board refueling vapor recovery, general points
The legislator requires that the refueling vapors 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.

On-board refueling vapor recovery, function sequence
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 fuel vapors through flow the safety valves (rollover valves) and fuel retention valve to the activated charcoal canister, where they are stored.

When the fuel tank is full, the float valve closes off the fuel filler neck. This ensures that the refueling nozzle shuts off more rapidly and overfilling is largely prevented.

If fuel reaches the safety valves, these close off the aeration and vent line to the activated charcoal canister and thus prevent fuel from flowing into the activated charcoal canister.
By means of a diaphragm, the fuel retention valve also prevents fuel from flowing into the activated charcoal canister.

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.