Fuel Pump Relay and Check Engine Light

[Charles Schwartz <cschwart@stern.nyu.edu>]

So here is the saga.

I'm driving along in my '86 4000S.  110,000 miles, runs good.  All of a
sudden, 100 miles from home, the car starts cutting out - like it's running
out of fuel.  I pull over, the car seems to be idling fine, gauges and
lights are okay.  I drive on and the problem gets worse.  I pull into a
service station, and the mechanic says it sounds like a bad fuel pump or
fuel pump relay.  He pulls out the relay, and indeed, it is toast.  It comes
apart in his hand.  He doesn't have another, so he hot wires the two
terminals where the relay plugged in - one goes to the battery the other to
the fuel pump.  This is just to get me home.  He puts a 15 amp fuse in the
fuse box  and warns me that if the fuel pump is going out, it will blow the
fuse.  By now the car has cooled down somewhat and I start home.  It runs
fine. Then the cutting out begins again.  I pull into another service
station.  They agree with the fuel pump diagnosis.  I leave the car for them
to replace the fuel pump and relay.  I come back and the car runs fine.
(They socked me for $90 labor for the fuel pump!)  The only problem is now
the Check Engine light won't go off!  I try disconnecting the battery for 15
minutes.  No good.  Then I notice that the new fuel pump relay has a 15 amp
fuse in the top.  The old one had a place for a fuse, but no fuse.  When I
take the fuse out.  The Check Engine light goes out.  But the light doesn't
even work with the fuse out.  Do I need this fuse?  Do I need this light?
The car is running fine.  Could the check engine condition be diagnosed
without getting re-circumcised by the Audi gods?  Please help.  I know this
is only a measly 4000S and not a turbo quattro convertible 30 valve orgasm,
but it is my only transportation for the moment.

Charles