Clicking from this… what is it?

[G-Sting]

When the key is turned to electrics on, but prior to start, this clicks quite audibly ever 1.5 seconds. What is it, and is it supposed to make that sound? It's located under the hood up towards the right front facia of the '94 Z.

(BTW, Z manuals are on order!)

[XfireZ51]

Secondary vacuum pump. If its turning on every few seconds, you have a vacuum leak somewhere in the system.

[We Gone]

Sounds like it is trying to cycle on once on it should run at least a few seconds. It is the vacuum pump for the secondary's. It may be repairable. Check out Dynomite's sticky's or I'm sure he will post up a link.

[Dynomite]

Originally Posted by We Gone

Sounds like it is trying to cycle on once on it should run at least a few seconds. It is the vacuum pump for the secondary's. It may be repairable. Check out Dynomite's sticky's or I'm sure he will post up a link.

VACUUM SYSTEM
Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC) TIPS
Checking for Vacuum Leaks TIPS
Failed Vacuum Check Valve TIPS
Finding Vacuum Leak TIPS
Condition of Secondary Vacuum System TIPS
Vacuum Pump Taken Apart TIPS
Differential Pressure Switch Function TIPS
Secondary Vacuum Removal TIPS
HVAC, Brake Booster, and Purge Vacuum Leaks TIPS
Secondary Vacuum Reservoir Source TIPS
Vacuum testing
Secondary port vacuum diagnosis
Secondary diagnosis
Vacuum solenoid
Trouble Shooting Secondary Vacuum System
Cruise Control Vacuum
Cruise Control Inoperable Diagnostics
Secondary vacuum diagram
Vacuum pump malfunction
Non operating secondaries
Vacuum pump vendor
Vacuum solenoid conversion
Check valve under plenum

Originally Posted by G-Sting

When the key is turned to electrics on, but prior to start, this clicks quite audibly ever 1.5 seconds.

You have a vacuum leak between the vacuum pump and Under the Plenum.

[G-Sting]

Originally Posted by XfireZ51

Secondary vacuum pump. If its turning on every few seconds, you have a vacuum leak somewhere in the system.

Got it, thanks all. Will begin to check it out.

The Z starts right up, idles great, runs smooth and like a beast. Appears to be all stock, 19k miles. Wasn't driven but 1,700 miles in the last 9 years.

Narrow it down any?

[Dynomite]

Originally Posted by G-Sting

Got it, thanks all. Will begin to check it out.

The Z starts right up, idles great, runs smooth and like a beast. Appears to be all stock, 19k miles. Wasn't driven but 1,700 miles in the last 9 years.

Narrow it down any?

Check between Vacuum Pump and Plenum first....then check Drivers side Plenum Vacuum Connection to see if the Check Valve under Plenum is leaking. Disconnect that vacuum fitting and hold finger over end of vacuum line to see if pump stops cycling...if pump stops cycling the Check Valve is leaking.

Checking for Vacuum Leaks TIPS
Finding Vacuum Leak TIPS

1. Secondary Vacuum System
The first photo shows details of the vacuum plumbing around the Secondary Vacuum Solenoid and Secondary Vacuum Reservoir Including the Check Valve. The second photo is the complete Secondary Vacuum System.

The Check Valve allows plenum vacuum to be seen by Secondary Vacuum Reservoir but does not allow plenum to see Vacuum pump vacuum.

[G-Sting]

Originally Posted by Dynomite

Check between Vacuum Pump and Plenum first....then check Drivers side Plenum Vacuum Connection to see if the Check Valve under Plenum is leaking. Disconnect that vacuum fitting and hold finger over end of vacuum line to see if pump stops cycling...if pump stops cycling the check valve is leaking.

Dynomite, that (in bold) did it! Holding finger over the end of the nylon vacuum line resulted in the vacuum pump cycling about every 10 seconds - much less often.

The rubber fitting appeared to be very lose, and I zip-tied it to hold the nylon vacuum line tighter, but no change in the 1.5s cycling of the vacuum pump. Must be the aforementioned leaky check valve?

Great pics, BTW!

[Dynomite]

Originally Posted by G-Sting

Dynomite, that (in bold) did it! Holding finger over the end of the nylon vacuum line resulted in the vacuum pump cycling about every 10 seconds - much less often.

The rubber fitting appeared to be very lose, and I zip-tied it to hold the nylon vacuum line tighter, but no change in the 1.5s cycling of the vacuum pump. Must be the aforementioned leaky check valve?

Great pics, BTW!

Vacuum Check Valve

Make sure it is installed correct direction

Unfortunately you have to remove Plenum to Replace Check Valve.

[G-Sting]

Originally Posted by Dynomite

Vacuum Check Valve

Make sure it is installed correct direction

Unfortunately you have to remove Plenum to Replace Check Valve.

I had been browsing about all those who've pulled the Plenum for various things… and was literally thinking yesterday "glad I don't have to pull the Plenum until way down the road on this low mile Z." lol

Well, in the meantime…

1. Is there any problem with driving it for a bit before I do this?
2. What does that vacuum pump do for the secondaries before start?
3. Trying to keep it stock… for a least a month or two or three… and drive and enjoy it. But, what else should one check or replace when finally pulling the Plenum?

Thanks for the tremendous help!
G

[Kevin]

Originally Posted by G-Sting

Got it, thanks all. Will begin to check it out.

The Z starts right up, idles great, runs smooth and like a beast. Appears to be all stock, 19k miles. Wasn't driven but 1,700 miles in the last 9 years.

Narrow it down any?

just replace every part you can.