[Vwdiesel] Switching off fuel solenoid for economy...

[Mark Shepherd]

Looking at the cross section with the solenoid plunger down
the vacuum produced when the piston withdraws will drop most
of the fuel that's down the exit bore into the chamber and
then back into the exit on the next thrust. The vacuum
effect will probably also help the capillary action [also
forced by internal pump pressure]along the piston  for
lubrication. IMO the diesel that is sloshing around will
lubricate a switched off pump indefinitely...
Doesn't the pump on a 1.9 have a position related switch on
the pump  accelerator arm  that could be modified to switch
fuel off?
Mark

Roger wrote...
A little clarification on the above, the feed pump is still
circulating fuel through the pump and returning it to the
tank with
the fuel cut-off solenoid is off.  But looking at the
diagram and description at:
 http://www.cs.rochester.edu/u/jag/vw/engine/fi/injpump.html
It seems the solenoid does opens and shut off the fuel
channel between the feed pump and the metering pump.
This would prevent fuel from filling the plunger, but there
is still likely some residual fuel left in the pump that
wasn't
injected on the previous stroke.  So maybe it is OK to run
it for a while w/o feeding fuel into the metering pump.
Never tried
it myself.
--
    Roger