Need help with vacuum leak

[detch]

Need help with a vacuum leak, when I turn on the car but not start it the pump keep running, when I pull the one hose off the driver side of the plenum and plug it the pump stops. I tried to pull a vacuum on the plenum's connector but it won't hold a vacuum. any ideas?

thanks
Mike

[LGAFF]

Are you testing vac off the P/S that is running from near the coolant overflow into the plenum? You should be able to hold vac if you plug your vac tester into the line running to the plenum. It should hold with slow leakdown at least.

If not there is a good chance you have a leak under the plenum.

LGAFF
92 ZR1
#234

[tomtom72]

If you can't hold any vacuum on the plenum side of the line you could see if you can find a vacuum check valve that fits the connector. Plug it into the line going under the plenum and re-do the vac test. If you hold vacuum upon the retest then you have solved the issue. There is a vacuum check valve in the hose network under the plenum that could have given up the ghost.

If that new check valve does not help, then the 2* control solenoid, reserve storage tank, maybe even the actuators or a leak in the actual hose are likely suspects. Unless you are setting a DTC61, I would say that the actuators are okay. To get an eyeball on what is under the plenum use this link.

http://www.corvetteactioncenter.com/...ad.php?t=14272

some great stuff that gives a great explaination.

[detch]

the vacuum is from the electric vacuum pump in the fron passanger side of the car. I check the hose from the check valve to the pump and they are fine, I wanted to check the connections on the outside of the plenum, when I remove the hose from the manifold vacuum (6e3-c2-6 fig c2-7 block #2) in service manual and pluged it, the moter stops, so I think the leak is between this connector on the plenum and where ever it goes, I just don't know where it goes.
I not talking from the connector to the check valve under the plenum I talking the other way from the connector on the plenum into the plenum



Mike

Originally Posted by detch

the vacuum is from the electric vacuum pump in the fron passanger side of the car. I check the hose from the check valve to the pump and they are fine, I wanted to check the connections on the outside of the plenum, when I remove the hose from the manifold vacuum (6e3-c2-6 fig c2-7 block #2) in service manual and pluged it, the moter stops, so I think the leak is between this connector on the plenum and where ever it goes, I just don't know where it goes.
I not talking from the connector to the check valve under the plenum I talking the other way from the connector on the plenum into the plenum



Mike

From the driver side port, the line goes into a check valve, then from there goes directly into a "T" port on the line. The two other sections of the "T", 1 goes to the vacuum pump, the other goes to the vacuum reservoir.

[rhipsher]

Check valves don't give up the ghost. They just get dirty and clogged. There are actually two check valves under the plenum. One in the front and one in the back. Easy way to check it is to unhook it and block the single perpendicullar outlet with your finger and blow through the other two ends. It should only allow air flow in one direction. If you are able to blow air through in both directions then its got dirt in it. All there is is a little bee bee ball inside of it. Just take some carburator cleaner and spray it in all the outlets. Then blow it dry. Then take some WD40 and also spray it in all the outlets. Check valve will be as good as new. But hell what do I know. Also when it comes to secondary port throttle failure be suspicious of the secondary vacume solenoid. It has a little cheesy air filter on it and over the years will evetually get old and turn to dust allowing contaminents to get sucked up into it and cause it to fail giving you that "Run out of breath at 4000rpm''s old man caugh under hard acceleration (SES light)error code 61 BS".

Originally Posted by rhipsher

Check valves don't give up the ghost. They just get dirty and clogged. There are actually two check valves under the plenum.

Two check valves, only one is causing an issue with the secondary operation. One for the cruise and one for the secondary system.

[rhipsher]

Just stating the fact that there are two check valves under there. I never said they both affected the secondary vacum operation. But while he's under there he might as well clean both of them. Unless you never use cruise control. But since you are more of a ZR-1 genius than me you can help him out. I'll just stay out of it. Why should I care, as long as mine runs fine. Right! Sorry detch I hope you figure it out soon. Jeffvette should be able to get you all fixed up and running. I'll just mind my own business next time somebody needs help.

Originally Posted by rhipsher

Just stating the fact that there are two check valves under there. I never said they both affected the secondary vacum operation. But while he's under there he might as well clean both of them. Unless you never use cruise control. But since you are more of a ZR-1 genius than me you can help him out. I'll just stay out of it. Why should I care, as long as mine runs fine. Right! Sorry detch I hope you figure it out soon. Jeffvette should be able to get you all fixed up and running. I'll just mind my own business next time somebody needs help.

Whoa....... I just didn't want him poking around looking for a second check valve on the secondary system. I've seen people mention problems on a 90, which has a few different systems and people with later cars suggesting to check this piece, which the 90 doesn't have. The more info the better.

[65ZR1]

Wow, I think someone needs more sleep!