fuel cap release RENAULT MEGANE SCENIC 1995 Service Repair Manual

ANTIPOLLUTION
Fuel vapour recirculation
14
CANISTER - FUEL TANK CONNECTION
The canister is connected to the fuel tank filler
neck by a quick release union.
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In the filler neck, a separate circuit connects the
quick release union to the sealing valve.
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The sealing valve isolates the canister when the
fuel filler cap is removed.
When the fuel filler cap is in position, the valve is
open and the fuel vapour may be absorbed by the
canister.
14-7

FUEL TANK
Filler neck
19
ROLE OF THE VALVES
A) Over-filling valve
When the fuel filler cap is removed, the valve
is closed, locking a volume of air in the brea-
ther chamber. This prevents fuel from ente-
ring this chamber.
When the filler cap is replaced, the valve
opens and the fuel tank breather is again
connected to the canister.
B) Excess - insufficient pressure safety valve
If the fuel vapour recirculation circuit is
blocked, this valve prevents the fuel tank from
excess pressure (the fuel tank would other-
wise inflate) or insufficient pressure (as fuel is
used, the fuel tank would be crushed).
C) Restriction valve
This valve prevents leaded fuel from entering
the fuel tank.
D) Valve preventing leaks if the vehicle is turned
over
If the vehicle is turned over, this valve pre-
vents the fuel tank from emptying, either
through the pipe to the canister or the brea-
ther pipe (Diesel).
The fuel tank has a sealed filler cap and a ventila-
tion circuit.
The filler neck for unleaded fuel has:
- an opening which is narrower and incompati-
ble with a leaded fuel pump nozzle (lead would
pollute the depollution system: the oxygen
sensor and catalytic converter),
- a valve blocking the filling opening (C) (to pre-
vent fuel vapour evaporating or fuel coming
out of the tank).
Refitting the fuel filler cap releases the over-filling
valve (A), allowing the tank to breathe through
the breather.
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