I noticed that when I fill up with gas in this car, the gas cap never makes a sucking sound upon removal. Does anyone know whether that is its normal operation?

- I tested the EVAP valve on the canister,
and it seems to be working correctly.
- I correctly see vacuum on both of the
canister-related intake manifold ports
when engine is on and the throttle
is actuated.
- If I pull a vacuum, using my Mityvac, on
the vaccum line coming from the gas tank,
that vacuum does not leak off quickly, so I
think the gas cap is sealing well.
- However, if I activate the EVAP valve with
vacuum, and use my Mityvac to suck air
on the canister port which feeds fuel
vapors to the intake manifold, vacuum is
never pulled on the line feeding to the
fuel tank. (Instead, I think outside air is
pulled up through the bottom vent of the
canister.)

Is this how it is supposed to work?

Do fuel vapors just travel to the canister
through diffusion, and then get trapped
in the activated charcoal?

Are the trapped vapors later released
with heat from the engine compartment
and suction from the motor?


- Wayne

 

it is normal.