EVAP CANISTER
DESCRIPTION
The canister mounts to a bracket on top of the fuel
tank (Fig. 1). The vacuum and vapor tube connect to
the top of the canister.
OPERATION
All vehicles use a sealed, maintenance free, evapo-
rative (EVAP) canister. Fuel tank pressure vents into
the canister. The canister temporarily holds the fuel
vapors until intake manifold vacuum draws them
into the combustion chamber. The Powertrain Con-
trol Module (PCM) purges the canister through the
duty cycle EVAP purge solenoid. The PCM purges the
canister at predetermined intervals and engine con-
ditions.
PROPORTIONAL PURGE SOLENOID
DESCRIPTION
OPERATION
All vehicles use a proportional purge solenoid. The
solenoid regulates the rate of vapor flow from the
EVAP canister to the throttle body. The PCM oper-
ates the solenoid.
During the cold start warm-up period and the hot
start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged.
The proportional purge solenoid operates at a fre-
quency of 200 hz and is controlled by an engine con-
troller circuit that senses the current being applied
to the proportional purge solenoid and then adjusts
that current to achieve the desired purge flow. The
proportional purge solenoid controls the purge rate of
ORVR System Schematic
1 – FUEL CAP
2 – RECIRCULATION TUBE
3 – LIQUID SEPARATOR
4 – PURGE
5 – W/LDP
6 – BREATHER ELEMENT
7 – W/O LDP
8 – CANISTER
9 – ROLLOVER VALVE
10 – FUEL TANK
11 – CHECK VALVE
12 – CONTROL VALVE
JX
EMISSION CONTROL SYSTEMS
25 - 23
DESCRIPTION AND OPERATION (Continued)