How Much Secondary Leakage?

[scottfab]

Just how much does your secondary vacuum system leak?
With your ign key turned on and engine not running
how much time does your aux pump stay off.
That is, once it runs for a time (maybe it keeps running)
how long (in seconds) does the pump stay off?

PLEASE if you deleted the secondary do not vote.
PLEASE use actual numbers, don't guess.
If you have more than one ZR-1 sorry you can only vote once
(only because I blew it when setting up the poll)
If your aux pump keeps running then the off time is 0 seconds.

[Dynomite]

I Concur with Marc :cheers:
If the vacuum pump cycles 5, 10, 15 seconds or at all....the vacuum system is NOT TIGHT but normal and functional for the age of the vacuum system with components not replaced with NEW LINES AND NEW RUBBER (soft) CONNECTORS.

Disconnect the drivers side center plenum vacuum source and hold your finger over the rubber connector disconnected (Engine OFF but Key ON). IF THE SECONDARIES (Secondary Canisters) FUNCTION AND HOLD POSITION WHEN TESTING SECONDARIES WITH PLENUM IN PLACE (Key on) Verifying Secondary Actuator Operation with the Plenum in Place (http://www.zr1specialist.com/HAT%20Web/articles/Verifying%20Secondary%20Actuator%20Operation.pdf) END OF DISCUSSION ;)

I will think further on this but for now I am busy planting corn and beans ;)

[scottfab]

Bwwwahhhhh ha ha ha ha
After this we'll have a poll on how many still have their tire pressure sensors in place and leave their tire pressure at 26psi.
And how many run their cars on bald tires.

I just remembered. I still check the washer fluid
every now and then but almost never drive it in the rain.
Kinda funny.

But seriously ......
I don't think Mark H. is advocating NOT to fix your
vacuum leak, just that a 1 sec cycle time will not effect secondary operation. Of that I'm not sure I agree. What I do know is that
if you have a leak big enough to cause a 1sec cycle time then there's not much wiggle room before you're at a bigger leak where as the pump runs constantly and you'll get a code 61 and loss of power above about 4000rpm. Just fix the dang thing before that.
It doesn't even take baling wire to fix just patience and the resolve to do so.

[We Gone]

91= 2.5 min.
93= 45 sec.

[scottfab]

91= 2.5 min.
93= 45 sec.


WOW! 2.5 min is the top score so far. She's tight!!!
I get 66seconds on mine.

[We Gone]

WOW! 2.5 min is the top score so far. She's tight!!!
I get 66seconds on mine.

Marc, just went thru the system when I had it up for the 510 package :dancing

[RICHARD TILL]

Pump runs one second every five. Have a new vacuum solenoid and MSD coils to install this week. New left side oxygen sensor yesterday as i moved it from right to left and the code followed. Rear tires are bald and the washer fluid is full.

[KILLSHOTS]

Just how much does your secondary vacuum system leak?
With your ign key turned on and engine not running
how much time does your aux pump stay off.
That is, once it runs for a time (maybe it keeps running)
how long (in seconds) does the pump stay off?

PLEASE if you deleted the secondary do not vote.
PLEASE use actual numbers, don't guess.
If you have more than one ZR-1 sorry you can only vote once
(only because I blew it when setting up the poll)
If your aux pump keeps running then the off time is 0 seconds.
Interesting stuff! Thanks for taking it a step farther and starting this thread, Scott!

[scottfab]

Interesting stuff! Thanks for taking it a step farther and starting this thread, Scott!

It's good to get things documented. When a reference is made to "average" ZR-1 then we know what's what.

[mike100]

I just recalled that the source of the leakage on mine was a real slow seepage out of the mini vacuum tank. This was a couple years back when I was testing the tubes with a handheld vacuum pump. It totally doesn't matter as the pump sucks air way faster than anything could possibly leak out besides a torn diaphragm.

I guess if my pump turned on every 5 seconds, I'd try to improve that, but otherwise it is just an academic discussion.

[Schrade]

Since I ripped & kludged [sp?] 'em out, I won't vote (just for you there Scott ;) ).

But I had timed mine to 1-2 sec's every 12-15 sec's, when I posted up about it... (http://www.zr1.net/forum/showthread.php?t=19252)

This is not normal. 10sec is too short of an interval.
It's easy to get it to 30sec or more.

DON'T rip it all out !
Just fix it like you would a burned out light bulb.
You also should not trade the car in for a new one
when the ash tray is full.

Start with the basics.
Find the hard plastic hose that comes out of the pump and
pull it out. Then put you finger over the side coming from the pump.
It should run a bit then stop for an indefinite period of time.
Report back then we can direct you to the next step.
(or find the old thread that covers this to send you too)

[scottfab]

Since I ripped & kludged [sp?] 'em out, I won't vote (just for you there Scott ;) ).

But I had timed mine to 1-2 sec's every 12-15 sec's, when I posted up about it... (http://www.zr1.net/forum/showthread.php?t=19252)


I try not to use terms like "kludge (https://www.google.com/#q=kludge)" and "ripped (https://www.google.com/#q=ripped)" out anymore. Some people find them upsetting and/or condescending along with "rattle can (http://www.urbandictionary.com/define.php?term=rattle%20can)" and "wonky (https://www.google.com/#q=wonky+definition)" :p
It's a "kinder gentler (http://www.ted.com/talks/alain_de_botton_a_kinder_gentler_philosophy_of_suc cess#)" world. :icon_scra
(click on each word for a deffinition)

[scottfab]

So far the average (leakage) time between cycles would seem to be greater than 5sec, much greater.

[weldbead]

moderator:
sorry i screwed it up.. i voted for greater than 30 seconds..in fact my pump runs(i stopped timing it after 60 seconds)

[Paul Workman]

moderator:
sorry i screwed it up.. i voted for greater than 30 seconds..in fact my pump runs(i stopped timing it after 60 seconds)

> 30 sec would include 60+ I would think. In any case you have a significant leak that requires attention.

Using a Mitivac (hand vacuum pump) one can isolate the problem fairly simply.

Here's a schematic of a 90, but the other years are quite similar, except the MAP switch is located under the ECM on the 90, but is under the plenum on 91+ cars.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/plenumvacuumcircuitsLT5Large.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/plenumvacuumcircuitsLT5Large.jpg.html)

The place to start is with the rubber connector on the plastic vacuum line, located on the plastic line, just as the line goes under the plenum. Pull it apart and put your thumb over the end of the tube. If the vacuum pump shuts off, then the problem is under the plenum (sorry). Otherwise the pump itself or the tubing or check valve is suspect.

Once under the plenum, you can use a Mitivac to apply vacuum and proceed to "divide and conquer" until the leaking component(s) are isolated.

The plastic vacuum line I've seen packaged in rolls at AutoZone. It can be cut to length and shaped with a heat gun or possibly a hair drier. Rubber connectors can be had in generic form as well as vacuum solenoid switches.

Stopping here, because this is OT. But, begin another thread (if you haven't already) and we can help ya isolate the issue, if need be.

P.

[fletchusmc]

Haven't voted yet and not sure if I should add this to this thread but, what's the difference in the way the vacuum pump should run with key on engine off or key on engine on? The reason I ask is I just went out this morning, turned the key on engine cold. Pump runs and doesn't stop. Started the engine and let it run for close to 10 minutes and the pump never came on (but does come on when I disconnect the vacuum line). Turned off the engine and immediately turned the key back on and now the pump is on off on off on off constantly.

Drives great all the way up to the limiter. Just wondering what the difference in engine on and engine off when it comes to the vacuum.

1995, #297. Stock except Corsas.

[Dynomite]

Haven't voted yet and not sure if I should add this to this thread but, what's the difference in the way the vacuum pump should run with key on engine off or key on engine on? The reason I ask is I just went out this morning, turned the key on engine cold. Pump runs and doesn't stop. Started the engine and let it run for close to 10 minutes and the pump never came on (but does come on when I disconnect the vacuum line). Turned off the engine and immediately turned the key back on and now the pump is on off on off on off constantly.

Drives great all the way up to the limiter. Just wondering what the difference in engine on and engine off when it comes to the vacuum.

1995, #297. Stock except Corsas.

You will see Vacuum Check Valve #15 in Paul's post (this diagram is for a 1990 ZR-1) which lets Plenum Vacuum take over when engine is idling and Plenum Vacuum is high. Vacuum pump takes over when engine has wide open throttle and Plenum Vacuum is lower. Cruise Control and HVAC on passenger side of Plenum and Secondary Vacuum on Drivers side of Plenum.

Secondary Vacuum System for a 1990 ZR-1.
http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/plenumvacuumcircuitsLT5Large.jpg

1. In your case you had High Plenum Vacuum at idle for 10 minutes (so vacuum pump remained off).
2. Pump came on when you disconnected vacuum line cutting off Plenum Vacuum to the pump.
3. With Key on and No Plenum Vacuum, Pump will cycle maintaining Secondary Vacuum as it is suppose to do. The more often the vacuum pump cycles the indication of more vacuum leaks present.
4. Pump cycling on and off every minute indicates minimal Vacuum Leaks under the Plenum. Pump cycling on and off every 5 seconds indicates Vacuum Leaks under the Plenum (Secondaries will remain operational as pump can keep up with the leaks if it cycles off no matter the cycle time).

When you first turned the key on and Vacuum Pump ran constantly......that might indicate the check valve #15 was stuck open or leaking and the pump could not build up vacuum because it was sucking air from the plenum.
Or....that might indicate with engine cold the vacuum leaks are unacceptable and with engine warmed up the Vacuum Leaks under the Plenum are significantly less (vacuum lines/connectors swell up closing down some vacuum leaks).

[5ABI VT]

Running out to the garage now to check mine.

[5ABI VT]

I unplugged from the passenger side where the tube goes into the plenum and capped it : 1:55 seconds before my fingers got tired. Plugged in.. 6 seconds and on for about about 1.

[fletchusmc]

Will have to do some digging around now. Later the same day I was finally able to get into an open enough stretch of road to open her up, ran all the way up to 7k like usual. I've got the FSM so obvious I need to do some homework on this part.

[Dynomite]

I unplugged from the passenger side where the tube goes into the plenum and capped it : 1:55 seconds before my fingers got tired. Plugged in.. 6 seconds and on for about about 1.

Passenger side is HVAC and Cruise.....I am confused....is that one minute 55 seconds.....whatever you capped on the passenger side...that has nothing to do with the secondary vacuum system.

It sounds like you are saying when you turn the key on (engine off) your vacuum pump is on for 1 second and off for 6 seconds which means you have vacuum leaks but are still functional on secondaries.

It would require you to start at the pump vacuum lines and work rearward to and under the plenum checking to see where that vacuum leak is located. Just unplug connectors and hold finger over side of connection coming from the Vacuum Pump. If Vacuum Pump quits cycling, the leak is beyond that point. If Vacuum Pump continues to cycle, leak is between that point and the Vacuum Pump.

Will have to do some digging around now. Later the same day I was finally able to get into an open enough stretch of road to open her up, ran all the way up to 7k like usual. I've got the FSM so obvious I need to do some homework on this part.

I appears that both of you have functional Secondaries which you can very easily check with engine off and key on........

See Secondary Functional Test and Reconditioning the Secondary Actuators (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-4.html#post1581665189)

[Hos327]

8 minutes!! Do I win something? Lol! 1990 with over 120000 on it. Had the plenum off for injectors and was going to tie open secondaries but thought if the system is that tight I?ll leave them active for now. Was shocked it was that tight as the car in not overly clean.

[Dynomite]

8 minutes!! Do I win something? Lol! 1990 with over 120000 on it. Had the plenum off for injectors and was going to tie open secondaries but thought if the system is that tight I?ll leave them active for now. Was shocked it was that tight as the car in not overly clean.

Your prize is a Functional Full Power Switch :thumbsup:
I have several posts within my signature related to upgrading/replacing the original vacuum lines and rubber connectors (which have hardened and shrunk with age) under the plenum :cheers:

I do these inexpensive replacements on all Zs as part of the Top End Restorations :dancing

[staminqia]

This is a great discussion as I have leak and my pump runs for 2 seconds and turns off for 2 second and then back on again. As of now I have no issue with secondary's. I find this odd but its the truth. I took it out for a 10 mile run with a ton of WOT and I had no codes or loss of power. What am I missing?

[ram_g]

...my pump runs for 2 seconds and turns off for 2 second ... I have no issue with secondary's. ... What am I missing?

You're not missing anything. According to Maestro Haibeck the secondaries will work fine even if the pump cycles off for only 1 second.

http://www.zr1specialist.com/HAT%20Web/articles/Are%20The%20Secondaries%20Working.pdf

[staminqia]

You're not missing anything. According to Maestro Haibeck the secondaries will work fine even if the pump cycles off for only 1 second.

http://www.zr1specialist.com/HAT%20Web/articles/Are%20The%20Secondaries%20Working.pdf

Yes agreed! Mine cycles off for about 2 seconds with no issues. I don't know if this question has come up yet but at how many seconds will secondary's stop working and then **** starts to shut down with the secondary's??? I would love to know to then trigger a plenum a removal!

thanks

[dredgeguy]

Yes agreed! Mine cycles off for about 2 seconds with no issues. I don't know if this question has come up yet but at how many seconds will secondary's stop working and then **** starts to shut down with the secondary's??? I would love to know to then trigger a plenum a removal!

thanks
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