John,
Here's a source of a gas leak I encountered last week on my '84 WBX: The
fuel injector rubberboots that connect to the fuel rail on both sides of
the engine. I temporarily fixed that by slipping a piece of heater hose
over it and clamping it down with worm clamps. It seems pretty much
fixed. My fumes are gone and so are the little puddles (!!!), thank god.

Just might be the case with your vanagon...