CGT 5k rpm cutout: Fuel pump relay number?

[Scott Fisher]

--- Huw Powell <audi at humanspeakers.com> responded to
EBavely (veetesse at hotmail.com), who wrote:
>
> > I immediately thought that the parts place
> > had given me a
> > 4-cyl FPR instead of the 5 cylinder one...

I'd bet you the cost of my first FPR-relay fix on my
'83 CGT that this is exactly what happened.  (Of
course, since that fix was free, neither of us will be
out much.)  The bucking, stumbling sensation is right
on the money, and it's exactly a rev limiter.  The FPR
reads ignition pulses, of which the I-5 has 20% more
per minute than a 4-cyl, and shuts off fuel when it
thinks you're near the limit.  Which is 20% lower in
an I-5 with a 4-cyl relay.

> quick test - remove it, bypass it, and see
> how the engine behaves.

Veetesse should check the Audifans archives, but I
believe it's as simple as jumpering the two biggest
slots where the FPR comes out.  (It was really obvious
when looking at it.) You'll hear the fuel pump start
when you plug in the jumper.  Meaning also that you
DON'T want to leave the jumper in 24/7.

As another free diagnostic, you can also pop the cover
off the relay (it's got slots on the sides), look for
the contact breaker points on a spring/magnet, and
wedge the contact points closed.  I got home that way
when my (old) relay failed on the way home from work.
In dicking with the old relay I weakened something in
it and it broke before I had bought the proper
replacement.  I coasted into a parking lot, made the
e-fix, and drove home.  There, I jumpered it with a
switch I happened to have lying around the garage,
then finally Did The Right Thing a few days later and
bought the factory part.

(That roadside fix was why I decided to buy the car --
I'd been borrowing it from a friend while I tried to
figure out what to do with another broken car.  When
this one quit on me and I was able to fix it with a
sliced-off piece of rubber from a squeegee, I decided
I HAD to own the car.)

> then drive the car over to the store and hope
> they actually *have* a 5 cyl relay.

If not, I bought mine at Carlsen Audi some four years
ago (check the Audifans supplier list).  I seem to
recall it wasn't cheap (so that may be the quickest
test: if you paid under $50 for the relay, it's almost
certainly a 4cyl unit.)

My '83 CGT's previous owner had put in the 4cyl relay
by mistake (the guy behind the counter picked one up
for an Audi 4000, which is the same as the
Golf/Rabbit/Jetta, and only something like $16) some
years before, but warned me when I bought the car that
it wouldn't run past 5000 RPM or so and he didn't know
why.  The quattro list came to my rescue that time,
almost five years ago.

Either way, it's worth getting it fixed -- 5000 RPM is
where it just starts to get fun!

Best,

--Scott Fisher
  Tualatin, Oregon



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