Sputtering and stalling - ? electrical, ? fuel system

[james.reed@iname.com (James Reed)]

Hi,

I've just bought a 1985 Scirocco 1.8 GTX. Generally it's running fine
but it seems to have an intermittent problem when running from cold (and
usually in damp conditions).

The engine will start and run for a while ok, but then at low revs the
engine will stutter and eventally stall, often with some pops and bangs
from the exhaust. Immediately afterwards it has trouble starting, but
after 10 - 20s it starts fine and then may do the same again at the next
stop. I can get around this to some extent by keeping the revs high
while driving and revving the engine while at a standstill. After a
while driving with high revs the problem seems to go away, and the car
can be driven for some time afterwards with no problems.

I've been wondering if this is an electrical problem - the car has a
voltmeter, and trouble is accompanied by the voltage dropping to about
9-10V while the car coughs and chokes (or is this just a consequence of
the stalling, rather than a cause?). I've noticed that the voltage is
affected by running electrical things (heated windscreen, fan heater
etc) and particularly flicks up and down when the indicators are on. Is
this normal, or could it indicate a dodgy battery? The local emporium
has put the battery tester on and it came out ok, but this was after a
long run. Given that the problem goes away after a while, could this
indicate that the battery has charged up a bit and is working properly
again? There is seldom much problem actually starting the car in the
first place, usually it is on the turn of the key.

The other idea I have had from reading the archives is a fuel filter or
fuel pump problem. Would this cause similar symptoms? Would they also
resolve after the car has been driven for a while?

I know I could eliminate the battery being at fault by getting a new
one, but at =A345 it would be a tenth of what I paid fro the car =
(=A3450!)
so a high proportion if the problem persists!

I'd be very interested to hear any suggestions. It's going in to the
garage (not VW agent!) later in the week for a check over, so would be
good to have a few suggestions for them.

Thanks in advance,

James