You are correct in assuming that your van was designed not to use that
filter. The outlet on your tank is going to be 11mm, while the outlet on
'80-'84 vans is 7mm. Thus, these earlier vans require the prefilter to adapt
the size from the 7mm tank outlet to the 7mm input on the filter, then an
11mm line from the large end of the filter to the input of the fuel pump.
Then 7mm all after the fuel pump.

Replacement tanks come with 11mm outlets.

'85+ vans do not have the provisions for that prefilter without adapting the
11mm line down to a 7mm before the filter. This often causes cavitation
which results in a loud fuel pump, hence the reason why VW went to all 11mm
line upstream of the filter.

My suggestion would be either search for a different manufacturer of large
particle prefilter with 11mm inputs and outputs, or just negate it. If your
tank is full of crap, your tank needs to be cleaned.
I just adapted my '85 to the '86+ style with the 11mm outlet on my new fuel
tank, so I've been there and been confused.... you're just going in the
opposite direction that I did.

-Craig
'85GL turned WESTY
BOSTIG in the back

On Sun, May 16, 2010 at 4:28 PM, Peter DiFalco <peter.difalco@gmail.com>wrote:

> I'm resealing the tank on my 89 today ... and yesterday (everything takes
> me
> 4X longer than regular people)... and anyway I am trying to reverse VW's
> bizarre decision to delete the large-particle pre-pump fuel filter (square
> one) and add one. So I bought the correct filter (at least according to the
> VW parts place) and I'm finding that the outlet on my fuel tank has a much
> larger ID than the inlet on the fuel filter. The outlet on the filter is
> actually larger, back up to the ID of the tank outlet, which matches the
> inlet on the fuel pump.
>
> So... either my fuel tank was specifically designed with a larger outlet to
> not use that filter and to plumb right to the fuel pump, or I bought the
> wrong fuel filter, or there's something else missing I can't imagine what.
> Please advise, oh wise list.
>
> I'm concerned that all my fuel tank manipulation and tilting and whatnot
> have dislodged some of those larger particles and I'd rather not send them
> through my fuel pump when I hook this sucker back up.
>
> One thing I'd thought of was picking up a PCV valve that has the two
> different diameter ports on it, and throwing it inline to step down the
> diameter prior to the filter. But I am not sure that randomly throwing
> valves around is a super good idea.
>
> -Peter
>