Acura NSX 1991 Manual page 280

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Evaporative Emission (EVAP) Controls
Description
The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The
system consists of the following components:
A. Evaporative Emission (EVAP) Control Canister
An EVAP control canister is used for the temporary storage of fuel vapor until the fuel vapor can be purged from the
EVAP control canister into the engine and burned.
B. Vapor Purge Control System
EVAP control canister purging is accomplished by drawing fresh air through the EVAP control canister and into a port
on the throttle body. The purging vacuum is controlled by the EVAP purge control diaphragm valve and the EVAP
control solenoid valve.
C. Fuel Tank Vapor Control System
When fuel vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and
regulates the flow of fuel vapor to the EVAP control canister.
EVAP
TWO WAY
VALVE
EVAP PURGE
FLOW SWITCH
Table of Contents
EVAP PURGE CONTROL SOLENOID VALVE OFF AFTER
STARTING ENGINE
ENGINE COOLANT TEMPERATURE ABOVE 153°F (67°C)
FUEL
FILL CAP
FRESH
AIR
EVAP PURGE
CONTROL
SOLENOID VALVE
EVAP
PURGE CONTROL
DIAPHRAGM VALVE
To No. 5 BACK-UP LIGHTS
ALTERNATOR TURN SIGNALS
(15 A) FUSE