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Warm Start Problem

Old 12-29-2015, 05:43 PM
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Default Warm Start Problem

98 ZJ starts fine when cold, but has problem starting after the engine gets warm, not all the time but enough to make it a pain. Replaced coil still does it. any ideas out there...
4.0 High Output I6

Last edited by moyneur; 12-29-2015 at 06:03 PM.
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Old 12-29-2015, 05:49 PM
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Welcome to CF, but we're going to need more info. What are you calling a 6.0? Do you mean a 4.0 I6 or a 5.9 V8?
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Old 12-30-2015, 07:36 PM
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Originally Posted by moyneur View Post
98 ZJ starts fine when cold, but has problem starting after the engine gets warm, not all the time but enough to make it a pain. Replaced coil still does it. any ideas out there... 4.0 High Output I6
Isn't this the "heat soak" issue some 4.0s have!?
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Old 12-30-2015, 10:15 PM
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Sounds like vapor lock to me.
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Old 12-31-2015, 06:43 AM
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Yes, and Mopar has a cure for it. There is an aluminum wafer heat shield that goes over the manifold and under the fuel rail. It sort of looks like cardboard to me! They put one on my 2000 WJ when it was recalled for seatbelt shoulder anchor bolts, a PCM reflash, and the heat shield. It's supposed to keep exhaust manifold heat from boiling the fuel in the rail and keep debris from catching fire. It seems the cast iron manifolds hold too much heat and don't cool off quick enough.

Being in a high temperature environment like SoCal, you're steel manifold is probably doing the same thing. There was a poster in AZ that had this problem and vented the hood supports to try to cool it down.

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Old 12-31-2015, 01:40 PM
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They also suggest wrapping one of the fuel injectors with a small heat shield. My 2002 has never not started, but has always started funky between 1-3 hours after running, starts perfectly hot or cold. I wrapped all my injectors and fuel rail with heat tape and vented my hood but have never cured the problem. They also make modules I believe that will run your engine fan after shut down and terminate based on time or temperature.
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Old 12-31-2015, 09:07 PM
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lurk520, that must have been you I just mentioned, right? I wondered how that venting worked.
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Old 12-31-2015, 11:31 PM
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I think so. It works somewhat, I remember checking temps on the hood with an infrared temp gun, the back where I drilled the exit holes was the hottest part, so heat was definitely getting out of there. Probably not as effective as installing Lebaron hood vents like some people do on their XJs, but it was easier and you wouldn't even notice it if you didn't know any better. Pretty sure I posted pictures in a thread some where.
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Old 01-05-2016, 08:41 AM
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Thanks, for the input, Keep you posted
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