[Vwdiesel] adjusting max fuel screw?

[Area31 Research Facility]

All,

I have had to add considerable back pressure as a negative side effect of
making my genset quiet out of respect for sleeping neighbors.  As a result
the engine appears to be running too rich. Fuel consumption is way up and
power is down.  Engine makes more waste heat, all bad consequences. :(  I
was wondering if I could lean it out a bit by adjusting the max fuel screw
on the Bosch FI pump.  Am I correct in assuming this is the one at the back
of the pump just above the fuel solenoid wire connection?  How does one
adjust it?  There are three adjustments, a nut, a sleeve with a wrench
purchase and a square head bolt at the end.  I'm thinking the nut closest to
the pump may be just a mounting nut and does not get lossened in the
adjustment.  I am running at 1800 RPM under throttle control by an external
mechanical governor.  Any ideas welcomed.

Thanx,
Rob