OPERATION
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 (Fig. 3) and then
adjusts that current to achieve the desired purge
flow. The proportional purge solenoid controls the
purge rate of fuel vapors from the vapor canister and
fuel tank to the engine intake manifold.
LEAK DETECTION PUMP
DESCRIPTION
The leak detection pump is a device used to detect
a leak in the evaporative system.
The pump contains a 3 port solenoid, a pump that
contains a switch, a spring loaded canister vent valve
seal, 2 check valves and a spring/diaphragm.
Fig. 1 ORVR System Schematic
1 – FUEL CAP
2 – RECIRCULATION TUBE
3 – CONTROL VALVE
4 – FLOW MANAGEMENT VALVE
5 – PURGE
6 – W/LDP
7 – BREATHER ELEMENT
8 – W/0 LDP
9 – CANISTER
10 – ROLLOVER VALVE
11 – FUEL TANK
12 – CHECK VALVE
Fig. 2 EVAP Canister
1– EVAP CANISTER
2– EVAP CANISTER BRACKET
LH EMISSION CONTROL SYSTEMS 25 - 21
DESCRIPTION AND OPERATION (Continued)
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