UPDATE- Stumped-Vacuum & idle

[NewVetter]

Maybe this sounds familiar to some here? Have a 1982 - Was trying to get at vent ductwork to fix a problem. Took gauge & shifter bezels off and was able to get at blk plastic ductwork for AC / def / htr, etc... Verified the cold/hot lever opened & closed that vac actuated metal 'door' in what I'd call the heat exchanger(?). Did just a general check of the vents, etc.. is all.

Anyway I believe I have SOMETHING bad going on now w/vacuum. Simply disassembling then reassembling these things in the interior, under dash, has now caused the car to: 1) It now barely idles, more like surges then almost stalls over and over. 2) The headlights never did come up, but now the driver side came up slowly. Just over all general erratic behavior. One good thing is maybe that tells me my headlight actuator is good(?) Haha. Will look next at vac can that JBP6000 mentioned on outside in pass fender, behind the inner one near kick panel. WILL report progress. :ugh
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UPDATE - (a little lenthy but necessary) First, Thanks to ALL here that replied to my issues. I learned much by taking things apart under dash... (took gauge & console bezels out [1982] to look at vent/ductwork cuz had hot air in cabin.) Now my apologies. I can now see how leaving out one seemingly minor thing can potentially change an outcome. Meaning, I said "Simply disassembling then reassembling these things in the interior, under dash, has now caused the car to:..." That was incorrect. When I started the car after checking under dash to find it now rough idled, I had NOT reconnected the gauges. As mentioned in the thread, I tried disconn the vacuum hose at manifold so as just to be able to drive it, but found it still had the rough idle. So I just decided to put the interior all back together then deal with it later.

Well.. apparently, just reconnecting the large electrical conn to the gauges, with what, 8 prongs per side, (and also the oil pressure 3 prong conn.), made the idle go back to smooth, as it was before I started the whole project. So correct me if wrong but I gather the vac system hoses, actuators, plenums, etc... can all be checked but the electrical must be there too via the gauges being connected. Again my APOLOGIES, for if I mentioned I had NOT installed the gauges again before trying, some here may have said, 'hey, you DO need to have the gauges connected too by the way. hahaha. Future postings, I will detail [exactly] what I did. I still have vac issues that I should be able to get through ok, but idle is great now and can drive it! Best regards, New Vetter

 

[82ColEd]

NewVetter: Bob Chadwick's website has a ton of trouble shooting tips and manuals here (under the Vacuum heading): CLICK

I hope those help you out, sorry i dont know exactly, but i have gotten lucky so far with mine.

-Stefan

 

[wishuwerehere82]

Get a vacuum gauge and measure your vacuum at the manifold fitting where the lines come off to the headlights, A/C. etc. You should have a good 18-21" of HG vacuum at idle.
Then measure the lines as they split off to the various functions. The plastic fittings and hoses under the dash are prone to cracking if you disturb them. Try blocking off each of the lines until the idle problem disappears.

 

[NewVetter]

Wish & 82, Thx for reply :>)
Say, just so can drive it without regard to AC, etc... No reason I cannot simply take main hose off of manifold and plug the manifold hole, right? i.e. eliminate the ENTIRE vacuum system so it at least runs correctly. It's only so my wife can at least drive it a little when home from vaca, then I can continue to tackle the issues at my leisure. (yeah separate vaca, haha NO jokes :>) she goes vaca, I get to crawl under a vette dash.

 

[Bob Chadwick]

That main supply line controls all the vaccum accesories unde the dash. Won't create any problems other than the vent system and the headlights.

 

[NewVetter]

Hi Bob, just read thru alot of your site... nice pics and descriptions. Will be going at the systems again today. Just so understand your ans to my last Q:, I believe you are in agreement w/me that I can disconn the main vac off the manifold and be good to go just to drive the darned thng, hehe. Have had it 2.5 mo. and driven it 140 mi.. Am not concerned w/AC & heat right now anyway... or driving at night for that matter, so lights no biggie though can raise em' manually anyway. again very nice site you have and kudo's to all the contributors you gave credit to, as well. Will report progress here on thread I started. Regards (All)

 

[Bob Chadwick]

Should be no problems. The heating and light circuit is seperate from the circuit for the vacuum advance and emission components. At least it is on the 77.

 

[wishuwerehere82]

Wish & 82, Thx for reply :>)
Say, just so can drive it without regard to AC, etc... No reason I cannot simply take main hose off of manifold and plug the manifold hole, right? i.e. eliminate the ENTIRE vacuum system so it at least runs correctly. It's only so my wife can at least drive it a little when home from vaca, then I can continue to tackle the issues at my leisure. (yeah separate vaca, haha NO jokes :>) she goes vaca, I get to crawl under a vette dash.

Yes, that will disable the heater, cruise control, and lights, and all the emmissions will still be conected.

 

[MMM]

I recommend you pull the right side panel off the console and check the connections at the back of the vacuum switch. It is easy to do this if you take the right seat out first. If the multi-hose vacuum connector is properly attached to the switch and you still have problems, remove the connector from the switch and plug the BLACK only hose. This is the main vacuum line in. You could also plug this line under the hood right above (and to the right side) of the vacuum brake booster. It is easy to find as it much smaller (~3/16" OD) and is teed in to a line approx. 5/16" OD.
My main design peeve with C3's is they are potential rolling vacuum leaks. Then on top of that GM equips most of them with a carb that requires a good vacuum signal to operate correctly. I believe many Quadrajets have been blamed for poor performance problems when the problem was actually a big vacuum leak elsewhere in the car. I could write pages on this issue.
Good Luck,
Mike

 

[wishuwerehere82]

Except the 82 is fuel injected. A vacuum leak produces a very pronounced change in the idle, surging, stalling like he has now.

 

[NewVetter]

UPDATE: Stumped-vacuum & idle

UPDATE - (a little lenthy but necessary) First, Thanks to ALL here that replied to my issues. I learned much by taking things apart under dash... (took gauge & console bezels out [1982] to look at vent/ductwork cuz had hot air in cabin.) Now my apologies. I can now see how leaving out one seemingly minor thing can potentially change an outcome. Meaning, I said "Simply disassembling then reassembling these things in the interior, under dash, has now caused the car to:..." That was incorrect. When I started the car after checking under dash to find it now rough idled, I had NOT reconnected the gauges. As mentioned in the thread, I tried disconn the vacuum hose at manifold so as just to be able to drive it, but found it still had the rough idle. So I just decided to put the interior all back together then deal with it later.

Well.. apparently, just reconnecting the large electrical conn to the gauges, with what, 8 prongs per side, (and also the oil pressure 3 prong conn.), made the idle go back to smooth, as it was before I started the whole project. So correct me if wrong but I gather the vac system hoses, actuators, plenums, etc... can all be checked but the electrical must be there too via the gauges being connected. Again my APOLOGIES, for if I mentioned I had NOT installed the gauges again before trying, some here may have said, 'hey, you DO need to have the gauges connected too by the way. hahaha. Future postings, I will detail [exactly] what I did. I still have vac issues that I should be able to get through ok, but idle is great now and can drive it! Best regards, New Vetter

 

[Bob Chadwick]

I don't know anything about the 82 other than it has a computer. Some reading was probably coming off that circuit and when it wasn't getting it, it was causing rough idle.

 

[82ColEd]

Happens to us all.. Thanks for coming back and clarifying. Hopefully it'll help someone out in the future. Glad you got the Idle back.