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  #1  
Old June 30th, 2017, 08:52
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Quailman Quailman is offline
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Heat Soak Issue

Hello I'm a new user here, just bought a white 1996 XJ with around 130k miles a couple days ago. First XJ!
I am however having a heat soak issue (I think).

I've been scouring the threads and a lot of people with this problem seem to have a rough idle or sputtering. Mine is a bit different. It has only happened twice so far, but it will basically just shut off when pulling into a parking spot (I guess I've just been lucky that it hasn't happened at a stop light).

It doesn't really "stall," just shuts off. No crazy noises or anything like that. Then, it won't start for about 1.5-2hrs when it fully cools down.
My current plan is to wrap the fuel injectors and surrounding area with heat shield tape to see if that helps.

Basically just looking for advice. FYI I do have CE codes for a downstream 02 sensor as well as P1899 which apparently is "manufacturer control; transmission," but I don't believe the P1899 to be related to this heat soak issue (although I could definitely be wrong).
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  #2  
Old June 30th, 2017, 09:16
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Nealio240z Nealio240z is offline
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Re: Heat Soak Issue

Welcome to the forum. Is this really your first post since you joined in February? What your describing does not really sound like heat soak. What operating temperature is your jeep at when she dies? Does it idle down and then die? Are you getting fuel to the rail after it dies with the key "on"? When it restarts does it stumble back to life or does it start up clean? It could be a number of things ranging from electrical gremlins to fuel pressure. I think we will need more information.
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  #3  
Old June 30th, 2017, 09:20
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Re: Heat Soak Issue

yeah it's my first post. Created the account in February for the hell of it but I just bought the xj on Wednesday.
The gauge is at around 210 when it dies, nothing out of the ordinary. Since it dies while pulling into a parking spot I'd say that it's already at idle when it dies. It starts up clean as long as I wait long enough for it to cool down.
Appreciate the quick response.
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  #4  
Old June 30th, 2017, 09:25
Green XJ Jeep Green XJ Jeep is offline
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Re: Heat Soak Issue

Clean your IAC and adjust the TPS
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  #5  
Old June 30th, 2017, 09:29
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Re: Heat Soak Issue

Quote:
Originally Posted by Green XJ Jeep View Post
Clean your IAC and adjust the TPS
I will try that when I wrap the injectors with heat shield. Would a dirty IAC be the cause if it doesn't start right back up afterwards?
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  #6  
Old June 30th, 2017, 09:50
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Nealio240z Nealio240z is offline
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Re: Heat Soak Issue

It is a good place to start. Temp it fine. Im thinking you have an electrical issue. We can drive and crawl these things everywhere, at any speed, and never experience heat soak. Have you checked if your fuel pump is priming after she dies? Only happened twice before tells me the fuel pump could be on its way out, or a fuel pump relay is toast. You need to verify fuel pressure. Ok once it dies again- crack the fuel bleeder valve on the fuel rail and let the pressure out (use damp rags and soak up the fuel- and be careful) then crank her over again and see if she fires. This will take out the hot fuel in the line if it is indeed heat soak. This will also tell you if you have fuel pressure at the rail after she dies. Also listen to the fuel pump to be sure that it primes again upon attempted start up.
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Old June 30th, 2017, 10:29
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Re: Heat Soak Issue

Quote:
Originally Posted by Nealio240z View Post
It is a good place to start. Temp it fine. Im thinking you have an electrical issue. We can drive and crawl these things everywhere, at any speed, and never experience heat soak. Have you checked if your fuel pump is priming after she dies? Only happened twice before tells me the fuel pump could be on its way out, or a fuel pump relay is toast. You need to verify fuel pressure. Ok once it dies again- crack the fuel bleeder valve on the fuel rail and let the pressure out (use damp rags and soak up the fuel- and be careful) then crank her over again and see if she fires. This will take out the hot fuel in the line if it is indeed heat soak. This will also tell you if you have fuel pressure at the rail after she dies. Also listen to the fuel pump to be sure that it primes again upon attempted start up.
All good suggestions. Thanks again everyone. Luckily I have a long weekend due to the holiday to do some trouble shooting.
I'll let you know how it goes.
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  #8  
Old June 30th, 2017, 10:47
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Re: Heat Soak Issue

Quote:
Originally Posted by Nealio240z View Post
It is a good place to start. Temp it fine. Im thinking you have an electrical issue. We can drive and crawl these things everywhere, at any speed, and never experience heat soak. Have you checked if your fuel pump is priming after she dies? Only happened twice before tells me the fuel pump could be on its way out, or a fuel pump relay is toast. You need to verify fuel pressure. Ok once it dies again- crack the fuel bleeder valve on the fuel rail and let the pressure out (use damp rags and soak up the fuel- and be careful) then crank her over again and see if she fires. This will take out the hot fuel in the line if it is indeed heat soak. This will also tell you if you have fuel pressure at the rail after she dies. Also listen to the fuel pump to be sure that it primes again upon attempted start up.
I think I'll just borrow a fuel pressure gauge from AutoZone to check the fuel pressure. Just to confirm, fuel pressure with regulator plugged in should be around 30psi and with regulator unplugged should be around 40 (in order to check both the pump and the regulator)?
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  #9  
Old June 30th, 2017, 13:12
Green XJ Jeep Green XJ Jeep is offline
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Re: Heat Soak Issue

Quote:
Originally Posted by Quailman View Post
I think I'll just borrow a fuel pressure gauge from AutoZone to check the fuel pressure. Just to confirm, fuel pressure with regulator plugged in should be around 30psi and with regulator unplugged should be around 40 (in order to check both the pump and the regulator)?
1996 is in tank regulator and fuel pressure should be 45 to 50 psi.

Could very well be the CPS starting to die but usually when they go out it just happens. In my case usually in an intersection.

People runs these thing pretty hard in Death Valley where it regularly gets to 115+ with out heat soak issues.
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  #10  
Old June 30th, 2017, 13:17
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Re: Heat Soak Issue

Quote:
Originally Posted by Green XJ Jeep View Post
1996 is in tank regulator and fuel pressure should be 45 to 50 psi.

Could very well be the CPS starting to die but usually when they go out it just happens. In my case usually in an intersection.

People runs these thing pretty hard in Death Valley where it regularly gets to 115+ with out heat soak issues.
I'll keep that in mind. At least if it is the CPS it's a cheap fix (although a PITA) lol.
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  #11  
Old June 30th, 2017, 13:22
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Nealio240z Nealio240z is offline
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Re: Heat Soak Issue

Quote:
Originally Posted by Green XJ Jeep View Post
1996 is in tank regulator and fuel pressure should be 45 to 50 psi.

Could very well be the CPS starting to die but usually when they go out it just happens. In my case usually in an intersection.

People runs these thing pretty hard in Death Valley where it regularly gets to 115+ with out heat soak issues.

This...
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  #12  
Old June 30th, 2017, 14:09
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Quailman Quailman is offline
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Re: Heat Soak Issue

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Originally Posted by Nealio240z View Post
This...
UPDATE: I got her home perfectly fine, tried to start back up and won't start again.
I cleared all CE codes to see if the "misfire" would throw a code which it did not.

I bled the fuel valve on the rail until the gas coming out was around ambient temp (seemed to be adequate pressure), then tried to start it and still won't start but cranks just fine.

I guarantee if I try again in 1-2 hours, it will start.
FYI it is 92 degrees here right now.
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  #13  
Old June 30th, 2017, 14:18
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Nealio240z Nealio240z is offline
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Re: Heat Soak Issue

Do you have spark? Maybe your coil is "heat soaked"... So you KNOW the pump is making pressure.

Fuel, ignition source (spark) and oxygen. You just ruled out two of them.
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  #14  
Old June 30th, 2017, 14:23
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Quailman Quailman is offline
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Re: Heat Soak Issue

Quote:
Originally Posted by Nealio240z View Post
Do you have spark? Maybe your coil is "heat soaked"... So you KNOW the pump is making pressure.

Fuel, ignition source (spark) and oxygen. You just ruled out two of them.
So you're saying it's most likely that it's either my ignition coil or my CPS? How can I test to see if that is the cause?
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  #15  
Old June 30th, 2017, 14:50
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Nealio240z Nealio240z is offline
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Re: Heat Soak Issue

You have to verify if you DO or DO NOT have spark when the symptoms occur. And yes, it can be either of those. I would replace the CPS first because likely it has not been done before- they seem to go between 65k-100k miles. Then look into ignition coil.

Btw: Have you done a tune up yet? Replace the distributor cap, rotor, wires, plugs, fuel filter, air filter, etc...
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