Both.  They're testing the gas caps and the evap system.

There's some light reading available here:

http://www.smogcheck.ca.gov/stdhome.asp

Cheers,

Jeff

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of Michael Elliott
Sent: Monday, March 03, 2008 2:18 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Calif 2008 emissions fuel tank pressure testing? /NO
Emissions Question

I are cornfused -- is CA testing gas caps or fuel tanks? Seems like some
folks have had one tested, others have had others tested.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR

On 3/3/2008 1:29 PM BenT Syncro wrote:

> On 3/3/08, Michael Hart <mjhart853@yahoo.com> wrote:
>> I just had my '87 Westy SMOG tested in the SF Bay Area (2/23)
>> As far as I remember, it was the same test procedure & equipment as 2
>> years ago.
>> The gas cap was tested off the van using a pressure hose & attachment.
>> There
>> was no pressure test of the gas tank. The machine used seemed several
>> years old.
>> This was at a 'SMOG Test Only' center, which they seem to send our old
>> vans to every time now.
>
>
>
> Just did 3 of my vehicles in the past week. All required off tank test of
> the cap. I used the same non-locking cap for all three cars just be be on
> the safe side. Ran into this issue last year. My locking cap gasket was
> supposed to be a leakerper their test equipment. So as a serial &
> multi-Vanagon owner, I keep a good known (newer) cap sitting around for
this
> purpose. I swap out my daily cap just before smog check time. Hasn't
failed
> me yet.
>
> On a separate note, I use the same cap for my Mercedes. Same cap, same
fit.
>
>
> BenT