Is Vacuum/ECM me problem? - JeepForum.com

 
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post #1 of 9 Old 05-06-2012, 09:28 AM Thread Starter
84VACJ7
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Is Vacuum/ECM me problem?

I have an 84 CJ7 6-258. It starts fine, runs fine.... sometimes. It seems that after it has been running a while the problems begin. It may cut out, may back fire, sometimes both. Once it cuts out it may restart, but then sometimes it has to sit a while before it will. It almost seems to me that when it warms up adjustments are made that throw things off. I'm handy, but not a true machanic. Any ideas? Thanks for any help.

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post #2 of 9 Old 05-06-2012, 09:48 AM
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First.....Welcome to the Jeep Forum, tons of stuff here for your CJ!

When the engine backfires, is it through the exhaust or the carb?

Sounds like your issue is heat related.

'86 CJ7, 258, Carter BBD, Nutter'ed, TeamRush'ed, T-18, Twin Sticked Dana 300, D30 Frt-Pwr Lok L/S-4.10, AMC 20 Rear-Mosers-Detroit Locker-4.10, 2.5 BDS Lift, 1" Body Lift, 33" Wild Country M/Ts, Black Spoke wheels

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post #3 of 9 Old 05-07-2012, 07:14 PM Thread Starter
84VACJ7
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It backfires through the exhaust.
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post #4 of 9 Old 05-07-2012, 08:57 PM
Trapshooter
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Any number of things could be happening. When was the last time the engine was tuned up? Double check you timing and look at the condition of the spark plugs. Pay close attention to the plug insulators, what color are they? You could have something as simple as a vacuum leak that manifests itself after the engine has time to heat up.

Please take the time to fully fill out your profile, this helps going forward when you have questions for the forum.

Do you still have all the emissions components installed on your '84? Is the engine still stock with the Carter BBD carburetor?

Here is a great Web site that explains all the emissions equipment your CJ came with: http://home.sprynet.com/~dale02/home.htm Take the time to look over this information as it will teach you "what is what" under the hood. If you live in an area where you do not have to pass an emissions test you can remove most of that stuff. Plenty has been written here to help you remove the unnecessary items.

Do take the time to unsure your carb is not coming loose where it bolts to the manifold. You can also take some starting fluid and spray around the base, if the idle increases you have a vacuum leak. Look over all the vacuum lines and fittings for any cracks or disconnects. Any open ports are a bad thing.

Good Luck...........

'86 CJ7, 258, Carter BBD, Nutter'ed, TeamRush'ed, T-18, Twin Sticked Dana 300, D30 Frt-Pwr Lok L/S-4.10, AMC 20 Rear-Mosers-Detroit Locker-4.10, 2.5 BDS Lift, 1" Body Lift, 33" Wild Country M/Ts, Black Spoke wheels

'45 CJ2A, L134 Go Devil, T-90 Tranny, Warn O/D, T-18 T-Case, Dana 25 Frt, Dana 41 Rear, 531st CJ made

My 401 build:
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post #5 of 9 Old 05-07-2012, 10:16 PM
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The ignition module will do most of your mentioned things. A bad coil will do the backfire.

Could be both.
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post #6 of 9 Old 05-07-2012, 11:50 PM
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Quote:
Originally Posted by 86cj74.2L View Post
The ignition module will do most of your mentioned things.
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post #7 of 9 Old 05-08-2012, 05:06 AM
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Have you Nuttered the computer?

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1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
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post #8 of 9 Old 05-08-2012, 05:10 AM
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Sounds like a bad ignition module, and perhaps a loose manifold bolt, or three.

Matt


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post #9 of 9 Old 05-08-2012, 03:16 PM Thread Starter
84VACJ7
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To all, thank you for the input. I'll check on these things and do some reading. No I have not Nuttered. I'm not real familiar with the process in Virgina and I don't know how hard the annual inspection guys will look at that.
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