Included in the possible vacuum leaks are the shut-off diaphram itself. Start by pulling the brown vacuum line off the element (shut-off diaphram back of inj pump). Put a separate piece of line to the element start the engine and suck. If the diaphram is good the motor will die. If the diaphram is bad you will get a mouth full of black nasty diesel oil. Its easy to tell which condition exists (bg).

There are so many places that can drop the vacuum so you should start here.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician