MotorVac Cool Smoke EVAP Leak Detection System - Manual (Page 9)

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EVAP Test Procedure
CAUTION – Many automakers require the use of a non-combustible gas such as nitrogen to be used while
testing an EVAP system. This is because a heat source or spark could ignite fuel vapours when mixed with
air. The MotorVac Cool Smoke does not introduce a dangerous heat source. However, other sources of
spark or heat could be present in the surrounding area. The Cool Smoke can perform its functions using
conventional shop air.
Test Setup:
1. ALL tests with the MotorVac Cool Smoke are performed with the engine off.
2. For OBD-II EVAP systems when the vehicle’s engine is turned off the vent valve is normally open. Use a
scan tool to close the EVAP System in order to perform any leak tests.
3. Connect the Motorvac Cool Smoke’s red (+) battery clip to vehicle’s positive battery terminal; connect
the black (-) battery clip to a solid ground point as far from the battery as possible.
4. Connect shop air to the MotorVac Cool Smoke’s inlet located at the back of the machine. Be sure sup-
ply pressure to the machine is between 80-150 psi (5.5-10.3 bar).
5. Verify the vehicle’s fuel level is below the base of the fuel tank neck.
6. Locate the EVAP service port indicated by its green cap. Remove the schrader valve from the EVAP
service port using the removal tool (060-0008) Note: The Schrader valve is a left hand thread, turn
clockwise to remove.
7. Connect the service port adapter (060-0005) to the EVAP service port. Connect the Cool Smoke smoke
hose to the service port adapter.
EVAP System Overview
The vehicle’s Fuel Vapor Recovery System is the most neglected part of the vehicle’s emission
system, according to the Environmental Protection Agency (EPA).
The vehicle’s EVAP system is used to collect fuel vapors from the fuel tank. These vapors are stored in a
canister filled with activated charcoal. The EVAP system allows the fuel vapors to be drawn from the
canister and combust during certain operating conditions. This process is called canister purging since the
fuel vapors are purged from the canister. OBD-II requires Powertrain Control Module (PCM) monitoring for
proper operation of the EVAP system and for possible leaks to the atmosphere. A faulty EVAP system will
allow hydrocarbons (HC) to escape into the atmosphere.
Factory emission tests have determined that an EVAP system with a leak as small as .020 can yield
an average of 1.35 grams of HC per vehicle driven mile. This is over 30-times the current allowable
exhaust emissions standard.
In addition to causing HC emissions, failure of this system wastes fuel and many times creates custome
complaints of “gasoline odours”. With the introduction of On Board Diagnostics (OBD), the vehicle is ca-
pable of determining that its evaporative system has a leak. Unfortunately it can not tell you the location of
the leak. Prior to the technology in the MotorVac Cool Smoke, determining where a leak in the EVAP system
was had been a difficult and time-consuming challenge.
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