Leak Testing the EVAP System
Understanding Test Results
• If the ball never goes to the top of the flow
meter, this indicates a restriction in the EVAP
system. (Did you remember to remove the Schrader
valve from the EVAP port?)
• If the ball goes to the top of the flow meter
and then descends to the bottom of the
meter, this indicates a leak of less than .020" (the
allowable standard), or no leak at all.
• If the ball goes to the top of the flow meter
and does not descend to the bottom of the
meter, this indicates a leak in the system.
1. Position the flow meter's red flag to align with
the ball, as shown in Figure 5.
2. If the red flag indicates a leak greater than the
allowable standard (see Figure 6), continue to
introduce smoke into the system and look for
the leak.
• For intermittent leaks, watch the ball in the
flow meter while doing a wiggle test on the EVAP
system (hoses, connections, etc.). If the ball in
the flow meter goes up only when you wiggle a
component, this indicates an intermittent leak.
Continue to introduce smoke into the system and
look for the leak. Repair the leak, and retest.
Remember, there can be more than
one leak.
8
Set the Red Flag
Figure 5
.020"
or
2000—newer
vehicles
FAIL
above this line
A
pproximAte
F
r
low
Ate
Figure 6
.040"
or
1999—older
vehicles
FAIL
above this line
A
pproximAte
F
r
low
Ate