I Concur with Marc 
If the vacuum pump cycles 5, 10, 15 seconds or at all....the vacuum system is NOT TIGHT but normal and functional for the age of the vacuum system with components not replaced with NEW LINES AND NEW RUBBER (soft) CONNECTORS.
Disconnect the drivers side center plenum vacuum source and hold your finger over the rubber connector disconnected (Engine OFF but Key ON). IF THE SECONDARIES (Secondary Canisters) FUNCTION AND
HOLD POSITION WHEN TESTING SECONDARIES WITH PLENUM IN PLACE (Key on)
Verifying Secondary Actuator Operation with the Plenum in Place END OF DISCUSSION 
I will think further on this but for now I am busy planting corn and beans