try compressed air back through the outlet hose, with the gas cap off.
You'll hear bubbles from the filler.  I shoot air in my 84 whenever I
change the feul filter to blow off the internal screen inside the tank.
Golf tees are a great way to temporarily plug a fuel line.. while you reach
for the tools, etc.
   I've used about 30psi pressure, I think...
   Another trick is that "fuel saver" stuff...it is good for dissolving the
varnish-like stuff from ethanol gas... You might try running the tank
almost dry, then pour a liter or two of that into the tank and let it soak
the screen...then douche the tank a bit and drain it, shoot more air and
fill again.  Could save you dropping the tank...
   I've used that gas saver to clean Moto tanks and carbs...works amazing
when nothing much else will.  Good luck

On Sun, Mar 18, 2018, 3:15 PM Cunegonde <cunegonde.van.westfalia@gmail.com>
wrote:

> What do vwolks think of temporarily swapping inlet with return line?
>
> > On Mar 18, 2018, at 11:59, Cunegonde <cunegonde.van.westfalia@gmail.com>
> wrote:
> >
> > I added more gas to tank. No visible leaks with what I’d guess is 12gal
> total in the tank. Will leave a tarp underneath so I can see any leaks in
> the next hour or so.
>

On Mar 18, 2018 3:15 PM, "Cunegonde" <cunegonde.van.westfalia@gmail.com>
wrote:

What do vwolks think of temporarily swapping inlet with return line?

> On Mar 18, 2018, at 11:59, Cunegonde <cunegonde.van.westfalia@gmail.com>
wrote:
>
> I added more gas to tank. No visible leaks with what I’d guess is 12gal
total in the tank. Will leave a tarp underneath so I can see any leaks in
the next hour or so.