I'd put money on the hall sender way before the O2.
The O2 isn't active until heated, takes a little while.
Also check and clean all your grounds.

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Bob Mund
Sent: Monday, July 27, 2009 9:53 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Van not starting??

I was driving to work this morning when van died at a stop light.  Tried
starting her again with no luck.  Turns over fine but won't fire up.  Could
this be an O2 sensor problem or possible fuel filter?  When trying to start
her she is trying really hard to start, very strong turn over....  I'm sure
I'll walk to her later and she'll fire right up for me but I'd like to solve
this problem.  Thanks for any help.

Bob