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Troubleshooting '84 Jeep Laredo Issue


CC57

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Trying to help a friend diagnose the problem with his 1984 Jeep Laredo (6 cylinder, 117,900 miles)

 

1st time you start it, it idles fine for a bit and then just flat dies. Won’t re-fire.

 

Operating H2O temperature on the gauge showed around 140.

 

Wait a few minutes and it starts back up.

 

Did notice this: was idling a bit high (approximately 900). I blipped the throttle and it settled down at about 600. And ran fine for an extended time.

 

Suggestions please?

 

And thanks all

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84 jeep was not computerized if I recall - most likely a coil or ign module in dist. Check voltages in and out of mod and resistance in coil cold and again when hot (or after dies).

 

OBD started making its appearance in 84 - if this is a an OBD (has a check engine light) cycle the key on and off four time within 5 seconds (ending in ON) and the check engine light will flash any stored codes - ECU controlled engines transition from open loop to closed loop (where the computer takes over timing and fuel delivery - (enrichment in OBD carburetors) at 140 degrees.

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had a jeep p/u one time that did similar thing,was a white ceramic resistor mounted on the firewall grounding out when it got warm/hot.the insulation on the back had cracked over time and the element inside would expand and touch the firewall.if i let it sit and cool down,truck would start up, but if it was warmed up or hot you could forget it.not even sure you have the resistor,but being an 80's jeep,may have it.be worth checking,only one little screw holding the bracket to the firewall.

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dont know if this will help i have an 93 s-10 it backfired an quit runin an thuoght it was tinnin chain put it in an the truck would idle afew minites then die so changed the module still did the diein changed the dist with a used one still did it but not as bad then bought a new dist an its ok now so far an put it in yesterday mornin so it may be the dist on urs too

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... a white ceramic resistor mounted on the firewall grounding out when it got warm/hot. ...

 

Where exactly/approximatley is this resistor you and rpfan speak of: inside the engine compartment? Inside the cab? And approximately where?

 

This isn't my Jeep, so I have to head over to the owner's house to look at his Jeep. So if you can give me a general description of where it is mounted, I can look for it and try to either troubleshoot or replace it.

 

Thanks very much guys

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It could also be on your inner fender wells or on the approns just look around. It may have also changed in looks somewhat over the years. You could just go buy one and then you will know what it looks like. They arent expensive.

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...changed the dist with a used one still did it but not as bad then bought a new dist an its ok now so far an put it in yesterday mornin so it may be the dist on urs too

 

Distributor was changed out recently, so - at this time - I'm ruling that out.

 

But thanks.

 

Also,

 

I asked the Jeep owner fort he VIN. Turns out, it's a 1989 Jeep Wrangler Laredo, 4.2L 6 cylinder.

 

And it doesn't appear that the resistor was used on this model.

 

Any suggestions gentlemen?

 

Thanks all

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The first thing you need to check is if it is getting spark at the coil when it if not running. If it dosn't have spark check the (-) wire on the coil with a test light the light will turn on and off when cranking. If it dosen't there are three thangs that could be bad (1) Micro Computer Control Unit (MCU) it is located in the engine compartment left hand side under the coolant reservior. (2) Is distributor (3) Electronic Ignition Conrol Unit (ECU).

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