Secondary Vacumm Pump question???

[Roadster]

I have noticed that the Secondary vacumm pump under the right headlight assembly has been disconnected. Therefore the pump was never running. When I plugged it back in, the piump runs continuously. So with that thought in mind:
1-why and would the seconandaries operate?
2- is it safe to assume that the pump needs replacement, or am I missing something here in the way the system functions ?

Again, the engine runs great, and that first complete WOT was nothing short of amazing. And I would also assume that the secondaries are operational, as there is no reason to believe that they were ever disconnected, unless that was performed when GM Engineering owned the Vette for the first 2 years.
From my research on previous owners, it seems that not too many parts were replaced. And the latest fuel filter and spark plugs were changed within the last two thousand miles.

PS....I don't have any stumble or hesitation what-so-ever, when you press down on the accelerator, it is an instant response throughout the gears.

Still learning about everything, so any thoughts or info is appreciated.
Thanks...........................

[Dynomite]

Secondary Functional Test and Reconditioning the Secondary Actuators TIPS

Sounds like you have your secondary system removed. Someone then just disconnected the pump. Look down between the runners of the Plenum as shown in in the link and you should be able to see the secondary actuator arms (one each side). Also...do you see a vacuum line leading from the vacuum pump up and under the Plenum on the passenger front of the engine?

It seems to me that you would loose vacuum at Wide Open Throttle as Plenum Vacuum would drop and the secondaries would then close if they existed given the vacuum pump is disconnected. If you have the secondaries intact, and a complete vacuum system, you definitely have a BIG vacuum leak under the Plenum. The Secondary Functional Test would FAIL under the conditions you have unless the vacuum pump is JUST able to maintain Secondary Vacuum by running constantly.

Is the Vacuum Connection between the two runners on the Drivers Side of the Plenum blocked? If so...that would also indicate the Secondaries have been removed.

If you have a BIG leak in the Vacuum system you are out of luck under ALL conditions operating the secondaries. There is a vacuum check valve under the Plenum which holds vacuum provided by the pump when plenum vacuum is low...that check valve does not function the other way...holding vacuum when the vacuum pump is non functional.

Vacuum provided by the Drivers Side of the Plenum will allow the Secondaries to function under some conditions but once Plenum Vacuum drops you are out of luck with the Secondary Operation.....I am thinking.

[Roadster]

Cliff, thank you for your link, will try to get that done by the end of the day.

[Roadster]

Originally Posted by Dynomite

Secondary Functional Test and Reconditioning the Secondary Actuators TIPS

Sounds like you have your secondary system removed. Someone then just disconnected the pump. Look down between the runners of the Plenum as shown in in the link and you should be able to see the secondary actuator arms (one each side). Also...do you see a vacuum line leading from the vacuum pump up and under the Plenum on the passenger front of the engine?

Is the Vacuum Connection between the two runners on the Drivers Side of the Plenum blocked? If so...that would also indicate the Secondaries have been removed. [/B]

Ok after further investigation, I am now assuming that the secondaries are non-exsistent.....
1-pump was and has been disconnected. and from what I am trying to understand, is that with the pump being disconnected, there would be no way that the secondaries would be functional at all, is that a correct assumption???
2-looking down between the runners on each side, I do not see the secondary actuator arms at all. it just looks like an open space on each side.
3-the vacuum line is still connected from the pump and goes under the plenum on the passenger front of the engine, but it feels looser than it should under the plenum.
4-that vacuum connection between the two runners on both sides of the motor are still connected.
5-so I imagine that the secondaries could be eliminated, but everything was not removed in the process.....

[KILLSHOTS]

Originally Posted by Roadster

Ok after further investigation, I am now assuming that the secondaries are non-exsistent.....
1-pump was and has been disconnected. and from what I am trying to understand, is that with the pump being disconnected, there would be no way that the secondaries would be functional at all, is that a correct assumption???
2-looking down between the runners on each side, I do not see the secondary actuator arms at all. it just looks like an open space on each side.
3-the vacuum line is still connected from the pump and goes under the plenum on the passenger front of the engine, but it feels looser than it should under the plenum.
4-that vacuum connection between the two runners on both sides of the motor are still connected.
5-so I imagine that the secondaries could be eliminated, but everything was not removed in the process.....

If you can redline the car with the pump disconnected, then your secondaries are removed. If they were intact, you'd have a hard time revving past 5000. Just turned off my key and confirmed that about an hour ago.

[Roadster]

Originally Posted by KILLSHOTS

If you can redline the car with the pump disconnected, then your secondaries are removed. If they were intact, you'd have a hard time revving past 5000. Just turned off my key and confirmed that about an hour ago.

Hey, Chris, thanks for the confirmation on that.....
Still in the learning process with all of this, had no idea or reason to believe that the secondaries could or would be eliminated on my 94. And yes as stated before it does make sense that if the secondaries were in tact and the pump disconnected that the engine would not run as good as it does.
Now I need to find out who removed them and when.....hmmmmm!!!

[Dynomite]

Originally Posted by Roadster

Hey, Chris, thanks for the confirmation on that.....
Still in the learning process with all of this, had no idea or reason to believe that the secondaries could or would be eliminated on my 94. And yes as stated before it does make sense that if the secondaries were in tact and the pump disconnected that the engine would not run as good as it does.
Now I need to find out who removed them and when.....hmmmmm!!!

No.....you need to find out who clobbered up the Secondary removal and remove the plenum and do it right
Also.....you might have a modified chip to account for secondary removal......

Originally Posted by KILLSHOTS

If you can redline the car with the pump disconnected, then your secondaries are removed. If they were intact, you'd have a hard time revving past 5000. Just turned off my key and confirmed that about an hour ago.

It appears that you do not have functional secondaries....and possibly someone removed the secondary function without removing the whole secondary system (tying the secondaries open for example and leaving all the vacuum lines in place).

[Roadster]

Originally Posted by KILLSHOTS

If you can redline the car with the pump disconnected, then your secondaries are removed. If they were intact, you'd have a hard time revving past 5000. Just turned off my key and confirmed that about an hour ago.

Ok Chris, you got me in the mood, did my second complete WOT minutes ago (deserted road, no one around) out of 1st gear on a slight roll, looks like I shifted around 7200 r's just slightly above the 7k marking on the tach. Just unbelievable, I could do that all day long. Not a hiccup, just pure LT5 engine power....Coolant Temp @ 204* Oil Temp @ 208* fully warmed up motor....vacuum pump disconnected as usual, apparently no secondaries to be found......

[KILLSHOTS]

Originally Posted by Roadster

Ok Chris, you got me in the mood, did my second complete WOT minutes ago (deserted road, no one around) out of 1st gear on a slight roll, looks like I shifted around 7200 r's just slightly above the 7k marking on the tach. Just unbelievable, I could do that all day long. Not a hiccup, just pure LT5 engine power....Coolant Temp @ 204* Oil Temp @ 208* fully warmed up motor....vacuum pump disconnected as usual, apparently no secondaries to be found......

There's the Permagrin!

[Schrade]

Some 2nd vac pump breakdown / diags snappics here, starting post #346 http://www.zr1.net/forum/showthread.php?t=21439&page=9