[Vwdiesel] smoke screw

[peter blake]

  Hey all,
I haven't posted for a while but I thot I'd share a minor 
success story w my 91 na jetta.  Recently I've noticed enuf
smoke that it was embarrassing to drive the car. I thot that
maybe I needed injectors, or the pump might have got out of
time or, that pump had somehow got richer in the amount of
fuel it sent to the injectors.  I'm very cautious about messing
w stuff that I know little about, it is all to easy to "fix"
something until it is truly broken.  Anyways I figured out
where the max fuel screw was and removed the collar and backed 
the screw out about 1/3 of a turn. The smoke disappeared for
all practical purposes.  I could see just a little wisp near the top
of the rev range at full throttle.  I think I can live w that.
Hopefully this adjustment will improve my mileage fm about 35
back up to the 39 or 40 I routinely got driving around LA w a 
lot of stop and go and very little high speed freeway. I'm 
going to fill the tank and set the odometer and figure the 
mileage. Here's hoping.
 One question I have about all this is: did the max fuel
screw tighten up on its' own?  Or is there some internal pump
wear that causes the fuel delivery to increase?  Anybody have
any info about this? TIA
Peter