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Old 04-05-2014, 12:33 PM   #1
Join Date: Jun 2013
Posts: 2
1987 Engine Starts and cutsoff after high idle

I am finally admitting stuck. I have a 1987 Wrangler with inline 6cyl Jasper engine. I had a bad backfire issue and may have damaged the carburetor (Holley 2brl). The following is the list of what I have replaced:
- New Holley Carburetor (model 7448)
- New fuel pump
- New EGR valve'
- New O2 sensor
- Replaced 2 vacuum hoese and clamps
- Plugs, wires, dist cap, and rotor were replaced a couple of months before carburetor issue

Previous owners had a lot of things added and removed so a lot of open connectors. However, I was able to drive (albeit rough) without cutting off.

Now I can crank the engine and it idles high then slows down and cutsoff. Played a little with the idle only but cannot get it to stop cutting off. I am obviously missing something. Any ideas or even a good vacuum diagram would be very much appreciated.

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Old 04-06-2014, 09:19 AM   #2
Join Date: May 2011
Posts: 62
I had a like problem, mine would start and run very rough til operating temp. then smooth out. Turned out to be crank position sensor. This could be your problem

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Old 04-06-2014, 02:01 PM   #3
Join Date: Jun 2013
Posts: 2
Thanks. I will try that and let you know how it works out.
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Old 04-06-2014, 04:04 PM   #4
Join Date: Aug 2011
Location: north of St.Franisville La.
Posts: 2,071
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Do the 4.2s even have a crank position sensor? I know mine don't.
The Government can not give anything to anybody that it does not first take from someone else !
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Old 04-06-2014, 04:50 PM   #5
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Join Date: Apr 2014
Location: Rockport, TX
Posts: 27
You know I had that same problem with my 2.5 it happened in cold weather too. I just adjusted the idle screw on the throttle assembly. Now she runs great.
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Old 04-07-2014, 10:31 PM   #6
Join Date: May 2011
Posts: 62
Sorry, I do have a 4.0. Not sure if you have that sensor.

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