On all car (well, most) the filter is after the pump! On most car, the pump
is inside the tank, there is a, or some small screens attach to the pump to
filter the big ugly stuff, the filter is after to protect the FI system,
including the expensive injectors. Now, the problem with the Vanagon fuel
tank is that it is getting old and the screen inside are worned or partially
blocked... that is why, sometime, the pump make noise, not because the
filter is clogued but because the screen are... and suction is dificult,
this can also cause lack of power because the system is under pressure....
you can blow air inside the tank from that nipple, but it will only last for
a wile.

There is nothing wrong with putting the filter after the pump... what is
wrong is keeping that old tank when you always get the same probleme (noisy
pump, cloggued filter, lack of power...)

Another case of customers not listening

Cheers, Ben (i just tried cleaning mine, we will see....)
ps.: i cut open a tank... but i can't find the dargn pictures...