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Unread 06-05-2013, 05:50 PM   #1
ryancrotty
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Strange question about idle problem

Lately the jeep has been having issues starting up, but once it starts it will run fine until you let off the gas, and then it just dies it wont idle at all. I am figuring the venturi jets need to be cleaned. When i went to dive in and start cleaning this is what i found, i dont know if it looks quite right. Also there seems to be a missing vacuum tube. I have been constantly trying to figure out and redo what the PO has done. Any help would be great.

It seems to have the stock carter on there and i just re did the plugs, wires, cap , rotor and coil

Thanks again for the help i would be lost without jeepforum

Missing vacuum ?
[IMG][/IMG]

Is everything correct here?
[IMG][/IMG]

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Unread 06-05-2013, 07:45 PM   #2
INowUnderstand
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Is that port capped? If not that will make it idle like crap. That is manifold vacuum. I have the air cleaner dampners hooked up there.

Google adventures under the hood. Great diagram of what jeep should be.
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Unread 06-05-2013, 09:13 PM   #3
ryancrotty
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It is not capped, should it be ?
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Unread 06-05-2013, 09:39 PM   #4
INowUnderstand
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If its not used yes needs to be capped. Should be sucking air. If the problem just started then maybe a vacuum line fell off.

My engine ran ok, then worse, then not at all at idle as my vacuum lines degraded. New holes kept opening up.

Do you have a stock TAC air cleaner? That should go on that there from what I have seen. There are several stock vacuum layouts and it looks like that is not a computer controlled carb so you can ditch some if the vacuum lines. Just make sure you have what is needed hooked to the right source. Ported vs manifold vacuum. Don't know your level of vacuum knowledge but I have learned a bunch of basics here in the last couple of months getting mine sorted out.

Like I said check out that site and search for other vacuum layouts. It sure helps. I think some if the other diagrams show the ports on carb better.
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Unread 06-06-2013, 12:55 AM   #5
BagusJeep
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Ditto on the vaccuum hoses leaking and that port needs capping off, some use a short length of vaccuum tube with a golf tee or small bolt in the end. With vaccuum leaks you will have problems with starting and maintaining the idle, a very common problem.

When it is up and running again look down that carb and see if there is fuel dripping from the idle tubes. if so they are clogged. They should be flowing a small amount but steady.
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Unread 06-06-2013, 07:58 AM   #6
ryancrotty
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It does not have a stock air cleaner. So I just need to cap that port off?
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Unread 06-06-2013, 11:48 AM   #7
ryancrotty
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It all started after a trial ride. It was really mild and we only hit water once.
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Unread 06-06-2013, 11:57 AM   #8
texasdave
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If that goes to the fuel evaporation canister that could be part of the problem as well.
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Unread 06-06-2013, 12:04 PM   #9
titomars
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Cap that port and see if it idles better I am sure it will. In 81 that port supplies vacuum to the air cleaner too. Also just so you know the idle circuit does not get its fuel from the boost venturies. All idle fuel comes from two small holes under the throttle plates. the jets you are referring to are air bleeds for the main circuit which only operates at speed
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**Originally Posted by wm69 **
This is the kinda whiny crap I would expect to see in the JK forum. We drive rough riding, leaking, gas guzzling CJ's. Rattle can it and throw it in your Jeep.
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1981 Jeep CJ7 258 4.0 HO head, T-5, D300, D30, D44, SOA
1994 Jeep XJ 4.0 HO, AX-15 (My Beater)
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Unread 06-06-2013, 02:13 PM   #10
INowUnderstand
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Ya cap it off if you don't see a line to hook into it that fell off

On mine I'm pretty sure That port is manifold vacuum. Don't want the evap canister signal line hooked to that. Canister signal should be hooked up to ported so that it turns on the canister only when on the gas. The purge line is usually t-ed into the same line as the pvc line in the middle of the carb on the back side just over from that port.


If you compensate for vacuum leaks by backing out the idle screws it may run. Maybe not good but will run. I did this when mine would not idle. Got it started and could hear a line just sucking in air. Got all the leaks fixed including a leaking egr and it is running really steady at idle now. Went from not being able to squeal the tires on a turn to being able to without any carb adjustment
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Unread 06-06-2013, 02:23 PM   #11
LumpyGrits
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CAP IT!
That is where the vac. switches that should be mounted on the valve cover get their signal.
It's a 'live' port.
LG
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Unread 06-06-2013, 05:06 PM   #12
ryancrotty
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Sounds good thanks for all the help ill try and cap it when I get home from work and let you know, but with the luck I've had with this jeep it has never been the easy fix.
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Unread 06-06-2013, 05:57 PM   #13
86cj74.2L
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Quote:
Originally Posted by LumpyGrits
CAP IT!
That is where the vac. switches that should be mounted on the valve cover get their signal.
It's a 'live' port.
LG
The two yellow vacuum switches are on the firewall above the valve cover.

The three vacuum gizmos operate the Sol-Vac idle control and the upstream and down stream air pumps for the cat-converter.
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Unread 06-06-2013, 06:05 PM   #14
LumpyGrits
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Quote:
Originally Posted by 86cj74.2L View Post
The two yellow vacuum switches are on the firewall above the valve cover.

The three vacuum gizmos operate the Sol-Vac idle control and the upstream and down stream air pumps for the cat-converter.
Switches-'gizmos', not much difference
Bottom line is, that v'port needs to be 'pluged'.
LG
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Unread 06-07-2013, 08:24 AM   #15
ryancrotty
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So I capped it of and still have the same issues? What could it be vacuum leaks elsewhere?
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