Dodge dakota 2002 Service Manual page 2852

DR
VAPOR CANISTER (Continued)
(5) Remove each canister from upper support
bracket.
1 - CANISTER MOUNTING NUTS
2 - CONNECTING HOSE
3 - UPPER SUPPORT BRACKET
INSTALLATION
(1) Place each canister into upper support bracket
and install nuts. Refer to Torque Specifications.
(2) Install lower support bracket. Refer to Torque
Specifications.
(3) Carefully install vapor/vacuum lines. The
vapor/vacuum lines and hoses must be firmly
connected. Also check the vapor/vacuum lines
at the LDP, LDP filter and EVAP canister purge
solenoid for damage or leaks. If a leak is
present, a Diagnostic Trouble Code (DTC) may
be set.
NATURAL VAC LEAK
DETECTION ASSY
DESCRIPTION
Vehicles equipped with NGC engine control mod-
ules use an NVLD pump and system.Vehicles
equipped with JTEC engine control modules use an
LDP (leak detection pump). Refer to Leak Detection
Pump (LDP) for additional information.
Fig. 27 EVAP CANISTERS - REMOVAL / INSTALLATION
EVAPORATIVE EMISSIONS
The NVLD pump is located in the same area as the
leak detection pump. Refer to NVLD Removal /
4 - LOWER SUPPORT BRACKET
5 - OUTER CANISTER
6 - INNER CANISTER
Installation for additional information.
OPERATION
Vehicles equipped with NGC engine control mod-
ules use an NVLD pump and system.Vehicles
equipped with JTEC engine control modules use a
leak detection pump. Refer to Leak Detection Pump
(LDP) for additional information.
The Natural Vacuum Leak Detection (NVLD) sys-
tem is the next generation evaporative leak detection
system that will first be used on vehicles equipped
with the Next Generation Controller (NGC). This
new system replaces the leak detection pump as the
method of evaporative system leak detection. This is
to detect a leak equivalent to a 0.020 (0.5 mm) hole.
This system has the capability to detect holes of this
size very dependably.
The basic leak detection theory employed with
NVLD is the Gas Law . This is to say that the pres-
sure in a sealed vessel will change if the temperature
of the gas in the vessel changes. The vessel will only
see this effect if it is indeed sealed. Even small leaks
will allow the pressure in the vessel to come to equi-
librium with the ambient pressure. In addition to the
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