I had something similar happen to my 91. The pump sucked the tank up. My problem turned out to be the charcoal filter was plugged. The small hose at the bottom of the filter that goes into the frame of the bus at the 90 angle was some kind of mud bug that dried and ended up breaking the dirt. Just my $.02.
Good Luck
Kevin Plichta 

> Date: Tue, 28 Jul 2009 16:23:16 -0500
> From: StevenM@RED-ROCK.COM
> Subject: 90 Vanagon/Westy fuel problem
> To: vanagon@GERRY.VANAGON.COM
> 
> 15 yrs at driving a Vanagon and do my own work, yet this has me stumped.
> Recent loss of pwr while at highway speed. Acted as if it may be a fuel
> filter and I replaced. Immediate improvement. Happened again a few weeks
> later and left stranded on road side. Always have spares of pump and
> filters, as I am often where they can't be found. When I took pump off,
> inlet was clogged with sediment. Definite time for tank replacement and
> did so. No luck. Would crank and fire, just no fuel. Looked under to see
> that tank had sucked up in a concave manner, so took line off and blew
> out with air hose to pop back in shape. Would then start, but run for a
> few seconds and die. Tried with gas cap off, etc. took all fuel lines
> loose and blew thru them. No fix. Bench checked fuel pump and it
> pressures right up. Could the fuel pressure regulator valve been trashed
> with the suction that caused the tank to collapse? Something is not
> letting the system pressure equalize as the fuel level drops is all I
> can think of. Any ideas?  

_________________________________________________________________
Windows Live� Hotmail�: Celebrate the moment with your favorite sports pics. Check it out.
http://www.windowslive.com/Online/Hotmail/Campaign/QuickAdd?ocid=TXT_TAGLM_WL_QA_HM_sports_photos_072009&cat=sports