Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here XJ (84-01)
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Vapor lock, aluminum foil.

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Old Mar 20, 2022 | 05:50 PM
  #1  
Lynn Gräber's Avatar
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From: Nashville
Year: 2001
Model: Cherokee (XJ)
Engine: 4.0
Default Vapor lock, aluminum foil.

So. Summers coming back here in Nashville. Which means, so is heat soak and vapor lock. On a whim this morning I decided to try wrapping injector 1-2-3 in loosely folded foil. These have been the cylinders that throw a misfire code when it happens. Took 10 minutes.

well, I’ve been driving around all day today doing small errands, turning the jeep off for a few minutes and restarting. About 9-10 times. She started right up. No rough idle. Nothing.

Today would’ve definitely been a day it would’ve happened. It was 70 degrees. My xj stays pegged just under 210 when running. But when I turn it off in warmer weather the temp will creep up past 210. This was happening today. But smooth start and temp comes right back down to rest under 210.

I know there are kits that you can buy. But man, this cost me nothing.

will report back as temps get warmer here in middle TN.
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Old Mar 20, 2022 | 07:20 PM
  #2  
Old Man Minimalist's Avatar
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From: Indiana
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0L
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Sounds good. Keep us posted!
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Old Mar 20, 2022 | 08:53 PM
  #3  
Cummins93's Avatar
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From: Northern CT
Year: 1995
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Engine: Turbo 4.0
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Post some pics
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Old Mar 21, 2022 | 04:03 PM
  #4  
tech's Avatar
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From: Santa Clarita California
Year: 2001
Model: Cherokee (XJ)
Engine: 4.0L
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I made my heat shield that the injectors go though it and it covers the exhaust that heats the fuel rail and injectors the heat shield is three layers thick and works great



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Old May 24, 2022 | 03:05 PM
  #5  
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'Heat Soak' problem solved......my '98 XJ had stalling, no power, backfire, etc. from too much heat in engine compartment, see attached photos........


Rear of hood raised to cool engine better. Didn't want to cut hood for circulation and have rain on motor parts either. Rain falls down on firewall, ie. no electrical near.

Three 1/4"Aluminum plate a side for raised hood air circulation.

I used high temp insulating tape on injectors and fuel rail, currently no more issues of the 'heat soak'.
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Old Jun 12, 2022 | 12:27 PM
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Up Date......The hesitation and loss of power & backfire reared it's ugly problem again, but not as severe as before. I found the fuel line routed and parallel under the intake manifold several inches from exhaust pipe. I completely forgot to trace the rest of this line for the "Heat Soak" issue. I now have added insulating tape to surround the fuel line from the fuel rail to the firewall.
Our area of the country is forecast for 90* days next week, experiment is on..............
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Old Jun 13, 2022 | 12:47 PM
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This was the area/fuel line that I missed before, now wrapped with heat insulating tape/cloth as the rest of the fuel system, no more heat soak!

This is much easier to wrap after removing air filter box

This whole fuel line(near exhaust,can see in background) I wrapped from firewall to fuel rail.
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Old Jun 14, 2022 | 05:44 PM
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UPDATE!!....................My XJ performed absolutely great!! I'd give it an A+!! We had temps in middle 90's, 76* dew-point(humidity you can wear) aaaannndddd the Jeep didn't hesitate, backfire, or had any kind of loss of power due to the 'Vapor Lock'.
I think wrapping the fuel line under the intake manifold to the firewall did the trick.
Engine didn't overheat in traffic at all, temp needle was 'one thickness' past 210*, everything is great, extremely happy Jeep owner.
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