Re: Vacuum leak? Marc has me confused now!
 

there also is a small vacuum switch inside the secondary pump, it could be out of adjustment and not shutting the pump off when vacuum is reached.

Re: Vacuum leak? Marc has me confused now!
 

i've had my '94 for less than a month and have very little time on the road with it..point being i dont know if my engine is at full power or not.. my pump ran for several minutes without shutting off when i tried it with key on but engine not running, i turned it off because it seemed longer than any other pump in the poll..real quick it says i have a bad leak or leaks.. would appreciate yer thoughts..

Re: Vacuum leak? Marc has me confused now!
 

Weldbead, I see its your first post Welcome... do a search here on it lots of posts on what and how to check it out. Sticky at top of this section.

http://www.zr1.net/forum/showthread.php?t=16778

Re: Vacuum leak? Marc has me confused now!
 

Your engine produces the most vacuum at idol, and very little at full throttle, that's when the secondary pump goes to work. With engine off, key on, take the hose off the secondary pump and hold your finger over the outlet. Pump should stop. If it doesn't pump is bad or needs adjusted. You can check the rest of the system for vacuums leaks with a hand held vacuum tester, about $30 at sears. The system is not that completed.

Re: Vacuum leak? Marc has me confused now!
 

That is the exact thing that happened to me when I bought mine.
You'll REALLY feel the difference when the leak is fixed.

Here is one of many vacuum leak troubleshooting sequences.
Click on the link below
Vacuum Leak Troubleshooting

Checking for LT5 Vacuum Leaks
 

As others have suggested close off the vacuum line closest to the pump with your thumb (after line is disconnected) and if the pump does not stop...bad pump or bad vacuum line connection to pump (hold thumb over pump connection to determine if bad pump). You can continue to use that some process to locate the leak if pump stops (for a minute or more) with the first line block with thumb.

Disconnect the lined further along and if pump stops (or cycles less), leak is beyond that line you just disconnected. Keep going and if pump does not stop (or cycles less) when you hold thumb over end of vacuum line, you have found the leak (or one of the leaks). Fix that leak and then continue disconnecting lines for possible additional leaks if pump does not stop once that leak is repaired and reconnected.

It is usual that the leak can be found at locations where fittings are easy to disconnect (Some of those connections are nearly impossible to disconnect....go past them as it would be unlikely the leak will be at that connection). With this method you can jump in anywhere and determine which direction to go if pump stops (or cycles less) to locate additional leaks. This will also locate the leak if found at the drivers side check valve which blocks the vacuum path to the plenum when plenum vacuum is low.

Once ALL significant leaks are found, the pump will stop cycling after initial vacuum is reached for a minute or more. At that point you are in business :thumbsup:

Before you pull the Plenum, check the pump and line going under the Plenum. Also check the Drivers Side vacuum line going into the Plenum at center of Plenum. The leak could be that Plenum connection or the check valve under the Plenum.

Checking for Vacuum Leaks TIPS

Re: Vacuum leak? Marc has me confused now!
 

Keep in mind, there is a vacuum switch inside the pump that can be adjusted.

RIP has me confused now!
 

How do you adjust that pressure/vacuum switch inside the vacuum pump?

What do you set the vacuum pressure at for proper vacuum?

Re: Vacuum leak? Marc has me confused now!
 

Welcome onto the boards there. Post snappics of your Z there.


RIP - you see the adjuster here?

I did give a passing thought to what the controller mechanism was...

https://lh4.googleusercontent.com/-D...0/HPIM7531.JPG

Re: Vacuum leak? Marc has me confused now!
 

When you draw a vacuum the small white piston in drawn in, separating the points and shutting the pump off. With a hand operated vacuum pump you should be able to see the points open and close. You could try to use your mouth. Suck, baby, suck.