Robin, check Martin's URL:
http://www.cs.rochester.edu/u/jag/vw/engine/fi/injpump.html .  The screw
you want to turn OUT to make lean and IN to make rich is called the
full-load adjusting screw and is labled as such.  Try 1/8th turn at a
time, and you will likely need to make an adjustment to the idling
speed.

-Dana-

Robin Oomkes wrote:
>
> Good morning everyone,
>
> A couple of months ago I wrote about my diesel's loss of power - finally
> my shade tree mechanic did something about it - he says he's 'tuned' the
> fuel injection pump.
>
> Power is greatly improved, but under moderate to heavy acceleration the
> van smokes a lot (black smoke). Oil, oil filter and air filter are
> clean. A steady 60 mph gives no visible smoke. I don't really want to go
> back to the mechanic for what I hope is a simple correction.
>
> I know there must be a screw adjuster on the pump which sets the
> injection quantity. I'd like to turn it back a little. Trouble is, I
> don't know which screw it is. My (Swiss) Transporter manual (a bit like
> a Haynes) only mentions how to set the idle and highest speed, but
> doesn't mention this quantity screw, possibly for environmental reasons.
>
> Can anyone help?
>
> Regards from Holland
> Robin
> 84 Westfalia Joker D (old smokey)
> 90 Westfalia Atlantic TD (white as the driven snow)