Toyota Tundra (2015 year). Manual — part 1294
Text in Illustration
*1 Purge VSV
*2
Purge Line Hose (to Intake Manifold)
*3 Purge Line Hose (from Canister)
*4
Canister Pump Module
- Canister Pressure Sensor
- Leak Detection Pump
- Vent Valve
*5 Canister Assembly
*6
Fuel Tank Inlet Pipe Sub-assembly (Canister Filter)
1UR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System;...
*7 Fuel Tank Cap Assembly
*8
Fuel Tank
*9 Purge Line
*10 Bleeding Pipe
-
HINT:
The canister pressure sensor, the leak detection pump and the vent valve are built into the canister pump
module.
Text in Illustration
*1
Canister Pump Module
*2
Intake Manifold
*3
Purge VSV
*4
Throttle Valve
*5
Canister Assembly
*6
Cut-off Valve
*7
Fuel Tank
*8
Air Cleaner
*9
ECM
*10
Fuel Tank Inlet Pipe Sub-assembly (Canister Filter)
*11
Soak Timer
*12
Roll-over Valve
*13
Fuel Tank Cap Assembly
-
-
*a
EVAP System Circuit
-
-
NOTICE:
In this vehicle's EVAP system, turning the vent valve ON does not seal off the EVAP system. To check for
ECM and stored fuel vapors in the canister are purged into the intake manifold. The ECM changes the duty cycle of
the purge VSV to control purge flow volume.
The purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is applied to the
canister through the vent valve to ensure that the purge flow is maintained when the negative pressure (vacuum) is
applied to the canister.
1UR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System;...
The following two monitors run to confirm the appropriate EVAP system operation.
1. Key-off monitor
This monitor checks for EVAP (Evaporative Emission) system leaks and canister pump module malfunctions. The
monitor starts 5 hours* after the ignition switch is turned off. At least 5 hours are required for the fuel to cool down
to stabilize the EVAP pressure, thus making the EVAP system monitor more accurate.
The leak detection pump creates negative pressure (vacuum) in the EVAP system and the pressure is measured.
Finally, the ECM monitors for leaks from the EVAP system, and malfunctions in both the canister pump module and
purge VSV, based on the EVAP pressure.
HINT:
*: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition switch is turned off,
the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the ignition switch is
turned off, the monitor check starts 2.5 hours later.
2. Purge flow monitor
The 1st monitor
While the engine is running and the purge VSV (Vacuum Switching Valve) is ON (open), the ECM
monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not
created, the ECM begins the 2nd monitor.
The 2nd monitor
The vent valve is turned OFF (open) and the EVAP pressure is measured. If the variation in the
pressure is less than 0.4 kPa-g (3.0 mmHg-g), the ECM interprets this as the purge VSV being
stuck closed, and then illuminates the MIL and stores DTC P0441 (2 trip detection logic).
Atmospheric pressure check:
In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before and after
Text in Illustration
*1
ECM
*2
Soak Timer
*3
Purge VSV (On)
*4
Fuel Tank Cap Assembly
*5
Canister Filter
*6
Fuel Tank
*7
Leak Detection Pump (Off)
*8
Canister Pressure Sensor
*9
Reference Orifice (0.02 Inches)
*10
Vent Valve (Off)
*11
Canister Pump Module
*12
Canister Assembly
*a
EVAP Purge Flow
*b
to Intake Manifold
COMPONENT
OPERATION
Canister Assembly
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 (time current is flowing) (Open: ON; Closed: OFF).
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 have elapsed, ECM activates (refer to fig. 3).
1UR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System;...
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