LR3/Disco 3
GENERAL
The 4.4L V8 Evaporative emission (EVAP) control system reduces the level of hydrocarbons released into the
atmosphere by fuel vapor venting from the fuel tank. The system comprises a charcoal canister, purge valve and
interconnecting vent pipes and hoses. The vent pipes are connected to the system components using quick release
connectors.
Fuel vapor is generated by the fuel in the tank and the amount of vapor produced increases as the fuel heats up. Fuel
vapor can flow freely to the charcoal canister via the tank venting system. The venting system consists of roll over valves
and a liquid vapor separator mounted internally in the tank and then externally via a breather line. The breather line allows
the fuel vapor to flow to the charcoal canister via a 'Y' piece mounted on the filler head.
On NAS vehicles the vapor generated during refueling flows without restriction to the charcoal canister.
On all vehicles except NAS, the vapor is restricted in its path to the charcoal canister but can flow freely during the
refueling operation to atmosphere, via the filler opening.
The vapor passes into the charcoal canister where it is absorbed and stored by the charcoal. Because there is a limit to
the amount of vapor the canister can contain, the fuel vapor is purged from the canister when the engine is running and
burned in the engine.
PURGE VALVE AND HOSES
5
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Charcoal canister
6
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Fuel tank breather hose from tank
7
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Purge hose
8
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Purge valve
9
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Fuel tank
10
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Charcoal canister vent hose (All except NAS) or DMTL pump vent hose (NAS)
