Leak Testing the EVAP System
1. Verify the vehicle's fuel level is below the base of
the fuel tank neck.
2. Locate the vehicle's EVAP service port. Remove
the green cap and the Schrader valve located inside
the service port. See Figure 3. IMPORTANT: The
Schrader valve is installed with a left-hand
thread.
3. Install the EVAP service port adapter (provided
with the tester) into the EVAP service port.
4. Insert the supply hose from the tester into the EVAP
service port adapter. See Figure 4.
5. Press the remote start button to activate the tester.
At the beginning of the test procedure, the flow
meter's indicator ball is at the top of the scale. This
indicates the EVAP System is being filled, and there
is no restriction in the system at this time.
6. Close the vehicle's EVAP system vent solenoid.
Usually in less than 60 seconds – depending on
capacity and fuel system level – the ball will fall
within the meter's visible scale. Continue to fill the
system until the ball stops descending. This could
take an additional two minutes.
See Understanding Test Results on the next page.
7. It is not necessary to wait until the system is full
(indicated by the descending flow meter ball) before
looking for leaks. Use the spotlight provided to follow
the EVAP path and look for smoke exiting a leak.
You could also use a UV light (not supplied) to
search for UltraTraceUV
exact location of the leak(s). The longer the EVAP
system is allowed to fill with Diagnostic Smoke
vapor, the more fluorescent material will be
deposited.
Warning: To prevent personal injury
when using an ultraviolet light, wear
OSHA-approved, yellow, UV goggles. Never stare
directly into UV light or shine UV light on skin.
8. Repair the leak(s), and perform the leak test again
to verify the repair and be certain there are no
additional leaks in the EVAP system.
9. Reinstall the vehicle's Schrader valve using a
counterclockwise thread rotation. Reinstall the
EVAP service port green cap.
®
dye deposited at the
®
Figure 3
Figure 4
Tech Tips
The EVAP service port on OBD-II vehicles was designed with
a Schrader valve before this smoke-producing test procedure
was developed for diagnosing EVAP leaks.
Smoke, when passed through a Schrader valve, will partially
condense. It will not be dense enough to be effective for EVAP
leak diagnosis.
For this reason, when testing with smoke, remove the
Schrader valve before introducing smoke into the EVAP
system. Remember to turn the Schrader valve in a
clockwise rotation to remove it.
Turn the
Schrader valve
clockwise to
remove it.
Service Port
Service Port
Adapter
Supply
Line
7