My 87 has never had the pre-filter. It's a straight hose from tank to fuel pump.
Always wondered why. Seems like it would make sense to have one.

On 7/21/07, Sam Payne <bungeegull@hotmail.com> wrote:
> Thanks, Bob
>     I did a supply test before dropping the wbx engine, and remember the
> volume was a bit low, but not a lot. Fuel pressure static and at idle is
> ok right now. But the pump is definitely cavitating: I can see the pump
> spray air bubbles around the white plastic pre-pump filter, can hear the
> air bubbles pass through the pump in bursts, and can hear and feel them
> when I squeeze the return line with my fingers. I replaced the main filter
> about 1,000 miles ago and the prepump filter today. No difference. Air in
> the lines seems like it matches the running problems too--surging at all
> speeds, misses, sudden coughs, etc. Finally, when I took the supply line
> off the tank nipple I had the filler cap off and the gas dribbled out way,
> way less than I would expect it to move out of a hole that size in the
> bottom of a container.
>    I heard that '87 up vanagons didn't have the pre-pump filter. True?
> Could VW have stopped using it because it restricted flow into the pump?
>
>             Thanks, Sam
>