RE: How to Change Fuel Filter ('88 5KSQ)

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

After coming too close for comfort to rounding off a flare nut with a
standard open-end wrench I broke down and bought a set of flare nut wrenches
... I use them exclusively and have not had a problem on either the ur-q
with the fuel filter under the car or the 5kCSQA where it is in the engine
compartment.  I'm not familiar with a "Bahco" adjustable ... perhaps it
provides more than 2 or 3 points of contact on the nut surface and is pretty
stout to resist undesired adjustments while trying to loosen the fitting,
but a flare nut wrench is in contact with 5 of the 6 surfaces and has enough
material to resist flexing in any way.  IME, those flare nuts lock
themselves into the filter quite snugly.  For the hexagonal surface stamped
into the filter case it really doesn't matter as much ... I've used
everything from "Crescent" adjustables to the appropriately sized open end
wrench (preferred if I have it).  

I don't do anything special to try to relieve the system pressure other than
letting the car sit overnight before starting the process.  As you have
suggested I just put a rag in the places where the fuel is likely to
leak/spray and just loosen the lines.  

Phil's idea for repressurizing the fuel system is an interesting one ...
perhaps rather than replacing the fuel pump check valve I'll simply rig a
switch on the dash to the fuel pump relay ... ;-)

Steve Buchholz
San Jose, CA (USA)

	----------

	In message <19990406213737.29514.qmail@hotmail.com> "Christopher
Ritchie" writes:
	> The Bentley does not provide any instructions on how to change the
fuel
	> filter on my 1988 5000S Quattro.  Do I just unbolt it, and catch
the
	> spraying gasoline as best I can?  Or, is there a recommended
procedure
	> whereby the engine is run with the fuel pump disabled (pull the
fuse),
	> thereby depressurizing the system and emptying the filter?

	I can only describe my own approach.  I've given up on Crowfoots and
	standard wrenches for fuel lines - I use two Bahco adjustables.
These
	I place on the joint concerned, and wiggle while turning the
tightening
	screw.  Then I shout: "Eyes closed", close my own, and open the
joint.
	If I know the car has a good accumulator, I usually wrap an old
towel
	round the joint first.

	After re-assembling, follow the "Output Diagnostics" instructions on
	Scott Mockry's page ( http://www.teleport.com/~scottmo ) for the
	5000 ECU.  The first such "output test" uses a fuse in the fuel pump
relay
	to run the fuel pump - let it run for fifteen seconds or until an
	audible ticking from under the rear of the car abates.

	Incidentally - for those plagued by warm starting problems - the
"output
	diagnostics" guarantee an instant start.