Quote:
Originally Posted by zig
Still trying to learn the differences in the ZR-1 from the 96 LT-1 I have. When I turn the ignition on I hear the vacuum pump run and then shut off. How long should iut remain off before it kicks back on? Mine shuts off for a couple seconds then turns back on for about a second. The cycle repeats until I start it up. Is this normal or do I have a vacuum leak?
|
I think you have a vacuum leak....once you start it up, plenum vacuum takes over. The faster the vacuum pump cycles (engine off) the greater the leak. The fact it does shut off even for a couple seconds means the leak is not extreme....but often kind of normal for vacuum lines that have become hardened with age. I think everyone has some vacuum leak more or less without knowing it. Plenum vacuum can easily compensate for small vacuum leaks such as that I think once the engine is running.
The Plenum vacuum source is that little connection center of Plenum on Drivers side. The other side of Plenum vacuum connection is Cruize and HVAC Vacuum.
If the vacuum pump does not cycle once the engine is running, that is an indication the Plenum vacuum can keep up with any small leaks. Now when Plenum vacuum drops at wide open throttle you still have sufficient vacuum with the vacuum pump keeping up with the leaks.
But I will check this out tomorrow when I fire the 91' up again
OOPS...that will have to wait until I fire up the 90'....I have no vacuum pump on the 91'
