High Idle Issue

A small leak in the secondary system (pump cycling with the key in the on position and motor not running) will not cause any other symptoms. The engine provides the initial vacuum for the system and when the car is running the pump will be silent. If the leak is large enough the pump will come on when the secondary system is in use and it drops. The pump will come on and hold vacuum at 12".

[cuisinartvette]

Is it normal for the pump to come on at all with the motor off and the key in "ON" position, should you never hear it?

[1990 quasar blue]

Originally Posted by cuisinartvette

Is it normal for the pump to come on at all with the motor off and the key in "ON" position, should you never hear it?

About two years ago mine would give a quick blip (fraction of a second) every minute or so. I pulled the plenum and replaced the spider assembly. After that it would run once when the key was first turned on and then be silent. I stopped timing it after twenty minutes. Now it's back down to every two minutes again. If you have a leak just get a vacuum gauge and pull the plenum. It's pretty easy to track it down.
http://www.corvetteactioncenter.com/...threadid=14272

[cuisinartvette]

Cool...Sounds like I may have a slight leak..
I get a quick blip every few seconds before I turn it on. Runs good though..
Good excuse to port I guess.