Several things trigger a "deliver fuel" event in the d-jet
system. The most important are the switches on the distributor
which fire the injectors in banks of three. Another is the
contacts on the throttle position sensor which will fire all
the injectors when you transition from one contact to another
in the "open throttle" direction; this functions as an
accelerator enrichment mechanism. There is also a temperature
sensor thingy on a timer that will fire an extra injector
for cold starting.

If your car only runs when you pump the gas then it is
probably running only on the throttle enrichment function.
You should check the contacts on the distributor, to make sure
that they are connected and that they are working correctly.
These switches don't do much besides open and close, and they
don't deal with much voltage or current, so they shouldn't
wear out. You can probably get new switches at a junk yard
as well, but I'm not sure if they are specific to the B30
distributor or if you can get them from any d-jet system or
at least any d-jet volvo.
chris