Toyota Sienna Service Manual: EVAP System

Toyota Sienna Service Manual: EVAP System

Component

Operation

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 is 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 is controlled by purge VSV duty cycle ratio (current-carrying time). (Open: ON, Close: 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 is purged, valve closes and restrictor prevents a large amount of vacuum from affecting pressure in fuel tank. Valve is opened while refueling. When valve is open, adding fuel into fuel tank is possible.
Roll-over valve Located in fuel tank. Valve closes by its own weight when vehicle overturns to prevent fuel from spilling out.
Service port Used for connecting vacuum gauge for inspecting EVAP system.
Soak timer Built into ECM. To ensure accurate EVAP monitor, measures 5 hours (+/- 15 min.) after ignition switch is turned off. This allows fuel to cool down, stabilizing Fuel Tank Pressure (FTP). When approx. 5 hours elapsed, ECM activates
Canister pump module Consists of (a) to (d) below. Pump module cannot be disassembled.
(a) Vent valve Vents and closes EVAP system. When ECM turns valve ON, EVAP system is closed. When ECM turns valve OFF, EVAP system is vented. Negative pressure (vacuum) is created in EVAP system to check for EVAP leaks by closing purge VSV and vent valve (closed), and operating vacuum pump are turned on (refer to fig. 1).
(b) Canister pressure sensor Indicates pressure as voltages. ECM supplies regulated 5 V to pressure sensor, and uses feedback from sensor to monitor EVAP system pressure (refer to fig 2).
(c) Vacuum pump Creates negative pressure (vacuum) in EVAP system for leak check.
(d) 0.02 inch orifice Has an opening with 0.02 inch diameter. Vacuum is produced through orifice by closing purge VSV, turning off vent valve and operating vacuum pump, to monitor 0.02 inch leak pressure. 0.02 inch leak pressure indicates a small leak of EVAP.

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  • Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System

    Toyota Sienna Service Manual: EVAP System