Rav4 Rollover Valve

Toyota Rav4 2004 Repair Emissions

Components

Operations

Canister

Contains activated charcoal to absorb EVAP (Evaporative Emissions) generated in fuel tank.

Cut-off valve

Located in fuel tank. Valve floats and closes when fuel tank 100 % full.

Purge VSV (Vacuum Switching Valve)

Opens or closes line between canister and intake manifold. ECM uses purge VSV to control EVAP purge flow. In order to discharge EVAP absorbed by canister to intake manifold, ECM opens purge VSV. EVAP discharge volume to intake manifold controlled by purge VSV duty cycle ratio (current-carrying time) (Open: ON; Closed: OFF).

Refueling valve

Controls EVAP pressure from fuel tank to canister. Valve consists of diaphragm, spring and restrictor (diameter: 0.08 inch). When fuel vapor and pressure inside fuel tank increase, valve opens. While EVAP purged, valve closes and restrictor prevents large amount of vacuum from affecting pressure in fuel tank. Valve opened while refueling.

Roll-over valve

Located in fuel tank. Valve closed by its own weight when vehicle overturns to prevent fuel from spilling out.

Soak timer

Built into ECM. To ensure accurate EVAP monitor, measures 5 hours (+-15 min) after ignition switch turned OFF. This allows fuel to cool down, stabilizing EVAP pressure. When approximately 5 hours elapsed, ECM activates (refer to fig. 3).

Canister pump module

Consists of (a) to (d) below. Canister pump module cannot be disassembled.

(a) Vent valve

Vents and closes EVAP system. When ECM turns valve ON, EVAP system closed. When ECM turns valve OFF, EVAP system vented. Negative pressure (vacuum) created in EVAP system to check for EVAP leaks by closing purge VSV, turning on vent valve (closed) and operating leak detection pump (refer to fig. 1).

(b) Canister pressure sensor

Indicates pressure as voltages. ECM supplies regulated 5 V to canister pressure sensor, and uses feedback from sensor to monitor EVAP system pressure (refer to fig. 2).

Components

Operations

(c) Leak detection pump

Creates negative pressure (vacuum) in EVAP system for leak check.

(d) Reference orifice

Has opening with 0.02 inch diameter. Vacuum produced through orifice by closing purge VSV, turning off vent valve and operating leak detection pump, to monitor reference pressure. Reference pressure indicates small leak of EVAP.

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Responses

  • pimpernel
    How to repair fuel vapor cannister 08 rava4?
    4 months ago

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