I try my best here

LF +-----+ RF
   |    /|
   |   / |
LR -   | - RR
     VP+
        \
        + FD
        |
   TL ---

Where LF: left front door;
      LR: left rear door;
      RF: right front door;
      RR: right rear door;
      VP: vacuum pump, under rear seat;
      FD: fuel door, element accessed from trunk;
      TL: trunk lock
      +:  T or fork

Yours is 86 so LF, RF and Tk vacuum elements have electric wires
connecting to VP.  When any of these is unlocked/locked by key, VP will
be activated and open/close all doors.  Vacuum locks and pressure unlocks.

Front door vacuum tubes go up from floor into A-pillar.  Rear door tubes
go from B-pillar.  The tube between front doors go under the carpet,
just behind the fron bolts of seats.  The tube on RHS runs along the
right edge of the floor, also under carpet.  I don't recall exactly how
the rear tube goes.  It either tees from VP or from the RF fork, but I
am sure there is only one tube that reaches FD first then trunk lock.

All elements should hold vacuum for at least 1 minutes.  Use a hand
vacuum pump and some caps to test.  The hard plastic tube usually
outlasts the car.  Leak may be in element, then the rubber T or forks.
Retest vacuum after replacing anything.  There may be multiple leaks in
the same branch.