Vacuum Pump Sound

[robbz28]

Ok, I'm a new ZR1 owner...I have had this car for about 3 weeks now and I knew something wasn't "Right" about the car. Sometimes when I would romp on it, It wouldnt pull past 5200 or so, it would just plane out. Other times it would pull on up to 7k lickety split. After doing a little "googleing" I started reading about the secondaries and the vacuum pump. I discovered that my pump was locked up! So I took it off and opened it up and unlocked it, put a little grease down in it and it started working again! I know I have a leak somewhere under the plenum, I used a poor mans vacuum gauge (my mouth) and could tell the suction was being lost. I verified this later with a real gauge. So the pump will cycle on and off every few seconds. My question is what does the pump supposed to sound like? Mine makes a rapid puttering noise that you can easily hear from the drivers seat when you turn the key on. Sounds like a small motorboat almost. The reason I ask is I have pumps on my Tundra as well, but they are a lot quieter and whistle just a little bit. Just want to make sure my "fix" is actually fixed. (until i fix the leak of course)

[Daniel_Mc]

Robb,
I just replaced the pump on the Z and it has some noise to it. When I key the car up you can hear it very well in the drivers seat. Have you pulled the plenum yet to check the vacuum lines?

Daniel

[robbz28]

I ordered my gaskets for Jerry's monday to remove my plenum...It's a small leak somewhere under there.

You wanna know something funny...about 5 years ago I bought 4 of these pumps off of ebay, they were GM Hella labeled pumps. I got them for another project and do NOT know what I did with them. I think I gave like 30 bucks for all 4 of them...I need to do some digging! They are somewhere between my house and the 2 other placed I have lived since then, boxed away...

[scottfab]

First thing to do is test the vacuum on the pump. Many failures are in partial vacuum and/or internal leakage.
A slow leak under the plenum will not be an issue. the fact that you get an initial "pull" is a good sign that the leak under the plenum can be overcome.

Test pump.
1. unplug hose at the junction half way up to the plenum
(or right at the pump).
2. plug the pump end of the hose. The pump should run for a few seconds and stop. Hold the seal tight. It should NOT turn back on.
If it does or the pump runs for say 10seconds before shutting off
then the diaphragm is leaking inside the pump.

The good news is that these can be reworked. I just did this and posted a few pics. It will work until you get a replacement. Or in my case for another 10yrs until it fails again.

[robbz28]

Originally Posted by scottfab

First thing to do is test the vacuum on the pump. Many failures are in partial vacuum and/or internal leakage.
A slow leak under the plenum will not be an issue. the fact that you get an initial "pull" is a good sign that the leak under the plenum can be overcome.

Test pump.
1. unplug hose at the junction half way up to the plenum
(or right at the pump).
2. plug the pump end of the hose. The pump should run for a few seconds and stop. Hold the seal tight. It should NOT turn back on.
If it does or the pump runs for say 10seconds before shutting off
then the diaphragm is leaking inside the pump.

The good news is that these can be reworked. I just did this and posted a few pics. It will work until you get a replacement. Or in my case for another 10yrs until it fails again.

I tested the pump, I put my thumb over the inlet and it would turn off and stay off, as soon as I plug it back into the car it will run for 5-10 seconds then start to cycle on and off..it will run for maybe a second then stay off for 2 or 3, then on again....Definately a leak under the plenum. I got a mightyvac gauge yesterday and I can pump it up to 15 and it will slowly leak down to zero in about 3 to 4 seconds.

[scottfab]

Originally Posted by robbz28

I tested the pump, I put my thumb over the inlet and it would turn off and stay off, as soon as I plug it back into the car it will run for 5-10 seconds then start to cycle on and off..it will run for maybe a second then stay off for 2 or 3, then on again....Definately a leak under the plenum. I got a mightyvac gauge yesterday and I can pump it up to 15 and it will slowly leak down to zero in about 3 to 4 seconds.

Yah well that's not a slow leak you have. It's plenum pull time.
Sounds like check valve. Try applying the vacuum to the vacuum line
in the middle of the plenum on the driver's side. If the vacuum holds there (or leaks down from 15 to 10 in ten seconds or more) then it's likely the check valve or the fit of the hose on that metal tube you removed the line from.

[Paul Workman]

And, when you get tired of fussing with the vacuum secondaries, AND you want immediate throttle response, you can always just CHUNK UM! (Speaking of the secondary port throttles and associated stuff. Parts not in there seldom break, and don't cost much to replace!)



Most of the FBI gang are sans secondaries, and to a person, I don't know of anyone that would ever want to reinstall 'em ever!

Just a thought.

P.

[robbz28]

Yeah i got my plenum gaskets on the way. Can i get this check valve at autozone you think?

[Daniel_Mc]

Jerry is fast you should have everything soon. I just remembered I was looking for a leak on CJ's Z and found it was the vacuum line at the connector by the oil filter where it comes from the pump. No plenum pull required to check that one.

If you have my type of luck you will find the pumps... Just when you no longer need them LOL

Daniel

[robbz28]

Originally Posted by Daniel_Mc

Jerry is fast you should have everything soon. I just remembered I was looking for a leak on CJ's Z and found it was the vacuum line at the connector by the oil filter where it comes from the pump. No plenum pull required to check that one.

If you have my type of luck you will find the pumps... Just when you no longer need them LOL

Daniel

I have already checked that fitting...oh well, it will give me an opportunity to clean under the plenum, it looks kinda dirty under there. That's all I have been doing to this car since I got it. The PO (the original owner) did a decent job of keeping the car clean, but he never removed the seats or anything like that, so there is a lot of yuck in the cracks and crevices of the car.