1990 4.2L TAC System Issue - JeepForum.com

 
LinkBack Thread Tools
post #1 of 4 Old 08-12-2011, 08:22 PM Thread Starter
dcook35
Registered User
1990 YJ Wrangler 
 
Join Date: Jun 2011
Location: Lees Summit
Posts: 13
1990 4.2L TAC System Issue

I have a 1990 YJ with a 4.2L with stock air intake & BBD carb. The vacuum motor for the trap door assembly in the air intake has apparently failed. I started chasing down vac leaks due to high idle not settling down and the engine idiling fast/slow/fast/slow on it's own. When I put vac pump on the vac motor by itself it will not respond unless I assist it by pressing down on the linkage that attaches it to the air inlet door with my finger. I press it in while applying vac with a hand pump and it will not retract until it is almost bottomed all of the way down. Even then it is a partial response. It will not hold vac on its own and immediately returns to the uncompressed position so I am assuming the diaphram is ruptured / torn / hole in it etc.. The other vac motor for the heated air door works normally and will hold vac indefinately. I want to retain the factory setup and am having no luck in locating one of these vacuum motors online through any auto parts store or oem supplier website. Does anyone have any ideas other than local pick & pull? My local P&P does not have any 1990 Wranglers in stock at this time.
According to the OEM parts catalog there is no part number for the vac motor itself. It appears that it is part of the air cleaner assembly which has its own part number. Anyone have one of these for sale due to a carb swap? Any input will be appreciated.

dcook35 is offline  
Sponsored Links
Advertisement
 
post #2 of 4 Old 08-12-2011, 08:35 PM
dancytron
Registered User
1990 YJ Wrangler 
 
Join Date: Jun 2008
Location: st. louis
Posts: 1,956
Have you tried just cleaning and lubricating it with some silicon spray?

It should be the same for any 6 cyl wrangler before 1990 and I am guessing some CJ's and cherokees with a 4.2 before that.

You should be able to get one here. Lots of people change the carbs and put aftermarket air cleaners on.

If it was me, I'd disable it in the open position. It doesn't do anything except prevent gas fumes from getting out of the carb for emissions purposes and they'd never catch it on the visual emissions inspection they do during the safety inspection.
dancytron is offline  
post #3 of 4 Old 08-12-2011, 08:50 PM Thread Starter
dcook35
Registered User
1990 YJ Wrangler 
 
Join Date: Jun 2011
Location: Lees Summit
Posts: 13
I'm pretty sure the diaphram has a hole in it. I just checked it out again and noticed that I can hear it sucking air when I pump on the mitivac pump. I'm not worried about emissions inspection as we dont have that in my area. I do want to keep it factory correct though for my own reasons and a vacuum leak is a vacuum leak. I dont think there is any way (that I am aware of) to repair one of these vac motors.
dcook35 is offline  
post #4 of 4 Old 08-12-2011, 09:26 PM
dancytron
Registered User
1990 YJ Wrangler 
 
Join Date: Jun 2008
Location: st. louis
Posts: 1,956
Well, you should be able to find a used one.

Just for your information, if you are in Missouri, they are supposed to do a visual emissions inspection during the every 2 year safety inspection. How good it is varies wildly from shop to shop. They mainly look for the CAT, EGR valve, vapor canister etc, if they look at all, but technically any bypassed emissions equipment could be a fail.
dancytron is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
1990 2.5 Fuel Pressure Issue garyzimm YJ Wrangler Technical Forum 6 03-18-2011 10:33 PM
1990 jeep YJ 3.9 magnum swap fuel pump issue smaxwell944 YJ Wrangler Technical Forum 1 05-04-2010 07:18 AM
4.2L 1990 Jeep Intermittent run issue mrt0mjones YJ Wrangler Technical Forum 6 11-25-2009 09:37 AM
1990 wrangler ....Moisture effecting ignition system???? Outbounder YJ Wrangler Technical Forum 2 12-04-2006 09:21 PM
4x4 vacuum system problems 1990 wrangler 2.5 (wheres the red hose go?) zpmada YJ Wrangler Technical Forum 7 03-18-2004 07:27 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome