[Dynomite]

Originally Posted by We Gone

Sounds like it is trying to cycle on once on it should run at least a few seconds. It is the vacuum pump for the secondary's. It may be repairable. Check out Dynomite's sticky's or I'm sure he will post up a link.

VACUUM SYSTEM
Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC) TIPS
Checking for Vacuum Leaks TIPS
Failed Vacuum Check Valve TIPS
Finding Vacuum Leak TIPS
Condition of Secondary Vacuum System TIPS
Vacuum Pump Taken Apart TIPS
Differential Pressure Switch Function TIPS
Secondary Vacuum Removal TIPS
HVAC, Brake Booster, and Purge Vacuum Leaks TIPS
Secondary Vacuum Reservoir Source TIPS
Vacuum testing
Secondary port vacuum diagnosis
Secondary diagnosis
Vacuum solenoid
Trouble Shooting Secondary Vacuum System
Cruise Control Vacuum
Cruise Control Inoperable Diagnostics
Secondary vacuum diagram
Vacuum pump malfunction
Non operating secondaries
Vacuum pump vendor
Vacuum solenoid conversion
Check valve under plenum

Originally Posted by G-Sting

When the key is turned to electrics on, but prior to start, this clicks quite audibly ever 1.5 seconds.

You have a vacuum leak between the vacuum pump and Under the Plenum.