Vacuum question. Pls help
Thread Starter
Heel & Toe
Joined: Feb 2022
Posts: 20
Likes: 2
Vacuum question. Pls help
I have a 1987 corvette. Will not stay running with pcv valve hooked up. It is new. I’m thinking there is a vacuum line blocked somewhere.
I unhooked passenger side, bottom vacuum port on throttle body that goes down to purge valve. I cannot blow or suck any air through this line. Could the purge valve be stuck closed and that is my problem??? It’s also running a little rich. I think it’s all tied together
I unhooked passenger side, bottom vacuum port on throttle body that goes down to purge valve. I cannot blow or suck any air through this line. Could the purge valve be stuck closed and that is my problem??? It’s also running a little rich. I think it’s all tied together
Pro
Joined: Aug 2007
Posts: 509
Likes: 8
From: Livonia Michigan
Speaking from experience with my 87, I found several cracked vacuum lines and plastic connectors plus a mis-configuration. Once I replaced
all my lines an configured them corrected it ran much better. There should be a vacuum diagram under the hood. if not I can sent you a
picture of my diagram.
all my lines an configured them corrected it ran much better. There should be a vacuum diagram under the hood. if not I can sent you a
picture of my diagram.
Pro
Joined: Dec 2018
Posts: 733
Likes: 424
From: Wisconsin
2023 Corvette of the Year Finalist - Modified
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Are you saying that it won't run with the line hooked up or that it won't idle? If it won't idle with the line hooked up I would start
looking at the IAC. With the line disconnected you are creating a vacuum leak.
looking at the IAC. With the line disconnected you are creating a vacuum leak.
Thread Starter
Heel & Toe
Joined: Feb 2022
Posts: 20
Likes: 2
Yes mixed nutz,
wont stay running or correct idle with pcv valve hooked up. Iac valve is new.
min about 20 minutes I’m going outside to crank it with line on throttle body going to charcoal canister unhooked. I’ll report back soon.
im hoping this is my problem
wont stay running or correct idle with pcv valve hooked up. Iac valve is new.
min about 20 minutes I’m going outside to crank it with line on throttle body going to charcoal canister unhooked. I’ll report back soon.
im hoping this is my problem
Pro
Joined: Dec 2018
Posts: 733
Likes: 424
From: Wisconsin
2023 Corvette of the Year Finalist - Modified
2022 C4 of the Year Winner - Modified
Finalist 2020 C4 of the Year - Modified
It is possible that your IAC isn't working correctly. Taking the line off causes a vacuum leak which allows the car to idle. (Essentially the same thing the IAC does.)
Have you changed the minimum idle recently?
Have you changed the minimum idle recently?
Thread Starter
Heel & Toe
Joined: Feb 2022
Posts: 20
Likes: 2
Mixed nutz,
iac is new.
with pcv hooked and line to canister unhooked,
seems to run fine.
the line going to canister from throttle body,
you can’t blow or draw any air from that canister. I think it’s stopped up
iac is new.
with pcv hooked and line to canister unhooked,
seems to run fine.
the line going to canister from throttle body,
you can’t blow or draw any air from that canister. I think it’s stopped up
Pro
Joined: Dec 2018
Posts: 733
Likes: 424
From: Wisconsin
2023 Corvette of the Year Finalist - Modified
2022 C4 of the Year Winner - Modified
Finalist 2020 C4 of the Year - Modified
If the IAC is working correctly it should be able to raise the idle enough to run. It is possible that you got a bad new IAC, damaged wiring to the IAC, or the passage is plugged (did you replace the gasket between the throttle body and plenum?)
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