[s-cars] rear fuel leak pinpointed (almost)

[Varon H. Fugman]

My occasional vague fuel smell on my '95 S6 sedan near the right rear
outside of the car has evolved into a rather strong fuel smell after driving
when the tank is more than 1/2 full.

Although it didn't seem localized at fuel filler, I previously replaced the
gas cap as a "just in case" measure (good news, new part # for the gas cap,
now only $12 instead of $40.)  I also inspected under the car for any sign
of leaks, including the rubber bushings that support the fuel lines as
reported by some listers.  Nothing.

So yesterday, starting with 1/4 tank of gas, I opened up the round access
lid in the forward part of the trunk.  This let me see where the 3 lines
(supply, return, vent) and wiring connect to the top of the tank.  No sign
of leak, but plenty of dirt and dust around there!  Replaced access cover,
then drove 5 miles to gas station.  Removed cover, inspected again, no
change.  Filled tank.  Inspected again, no change.  Replaced cover, drove
home.  Removed cover, bingo!  This time there was a big wet area... most of
the top of the whole assembly was wet.

Eventually found a tiny fountain of gasoline coming out near the base of the
banjo bolt connection for the fuel supply line.  Loosening the gas cap to
relieve the pressure in the tank stopped the fountain, so I conclude the
leak is caused by a combination of pressure in the tank and a high fuel
level (and not by fuel line pressure.)

But what is leaking?  Is there a crack in the plastic assembly?  (The Bently
shows the "main" plastic assembly as part of the fuel level sensor--Vol I
C20-4).  Or is it leaking around  where the supply pipe from the fuel pump
comes thought the plastic assembly?

The Bently cautions not to remove the fuel sender if the tank is more than
2/3 full, so it looks like I need to remove at least 7 gallons before I go
further.

Anybody replaced the sender or pump that can shed any light on this?  Can
the locking ring be removed w/o special tool spanner 3087?  Any and all
advice solicited!

Varon "squirting in Springdale" Fugman
'95 urS6

P.S. Happy New Year!  (And what better way to spend the new year than
troubleshooting an urS-car fuel leak... :~> )