Clicking from this… what is it?

[G-Sting]

Originally Posted by Dynomite

Check between Vacuum Pump and Plenum first....then check Drivers side Plenum Vacuum Connection to see if the Check Valve under Plenum is leaking. Disconnect that vacuum fitting and hold finger over end of vacuum line to see if pump stops cycling...if pump stops cycling the check valve is leaking.

Dynomite, that (in bold) did it! Holding finger over the end of the nylon vacuum line resulted in the vacuum pump cycling about every 10 seconds - much less often.

The rubber fitting appeared to be very lose, and I zip-tied it to hold the nylon vacuum line tighter, but no change in the 1.5s cycling of the vacuum pump. Must be the aforementioned leaky check valve?

Great pics, BTW!