Mazda 2006 MX-5 - Fuel-Filler Cap Function [Lf]; Fuel-Filler Cap Construction;Operation; Rollover Valve Function; Rollover Valve Construction;Operation

EMISSION SYSTEM
01–16–12
FUEL-FILLER CAP FUNCTION [LF]
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• If the evaporative gas passage is closed for some reason, the fuel filler cap prevents the generation of positive
or negative pressure in the fuel tank, protecting it from deformation.
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FUEL-FILLER CAP CONSTRUCTION/OPERATION [LF]
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• Consists of a positive pressure valve, negative pressure valve, spring, and O-ring.
• When there is positive pressure in the fuel tank due to evaporative gas, the evaporative gas is released into the
atmosphere. When there is negative pressure, air is introduced to the fuel tank.
• The positive pressure valve and negative
pressure valve opening pressures are higher than
the check valve (two-way) built into the rollover
valve, therefore the positive and negative
pressure valves are normally not open.
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ROLLOVER VALVE FUNCTION [LF]
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• The rollover valve prevents fuel flow into the evaporative gas passage during sudden cornering or vehicle
rollover.
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ROLLOVER VALVE CONSTRUCTION/OPERATION [LF]
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• The rollover valve cannot be removed or installed as it is built into the fuel tank.
• The rollover valve consists of a float, and spring.
• The rollover valve utilizes a combination of float weight, spring force, and buoyancy. When the float is sunk in
the fuel, the float (valve) closes to block the sealing surface of the passage.
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SPRING
O-RING
POSITIVE PRESSURE VALVE
NEGATIVE PRESSURE VALVE
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SPRING
FLOAT
VEHICLE LEVEL
FLOW OF EVAPORATIVE GAS
FUEL LEVEL
ROTATED 180
°
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