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COMPONENT OPERATION Canister pump module 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). (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. *1 Canister *2 Reference Orifice (0.02 Inches) *3 Canister Pressure Sensor - - *a Canister Pump Module (fig. 1) *b Airflow *c Condition: Purge Flow *d Condition: Leak Check *e Vent Valve: Off (Vent) *f to Canister Filter (Atmosphere) *g Leak Detection Pump: Off *h Vent Valve: on (closed) *i Leak Detection Pump: on - - 1UR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: EVAP System;... |