Subject: Re: Fuel Tank Vent-

[Tom Winter]

In 4000 cars, a hum or buzzing is an indication that the pump is going bad.
By "noise" if that is what you mean, and the buzz/hummm comes from the rear
of the car (passenger side IIRC) then a new pump could be all you need.

I cannot attest to clanging, rattling or other sundry noises you may be
hearing. But the buzz? That's the first sign of a bad pump in my experience.
Others may offer different solutions/analysis.

Good luck.

Tom '95 S6 Avant
Former owner of an '86 4000 csq.