Will not start when hot

Tiny
61CHEVYIMPALA
  • MEMBER
  • 2003 KIA SEDONA
  • 3.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
Starts fine when engine is cool but when reaches normal operating temperature and cut it off will not start until engine cools down again then starts fine, turns just will not start until engine gets cool, only problem it has is no start when hot.
Thursday, March 25th, 2021 AT 10:09 AM

6 Replies

Tiny
61CHEVYIMPALA
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Not starting when it reaches normal driving temperature is the only issue. Runs fine I could drive it all day and not have any problem from it if I don't shut it off
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Thursday, March 25th, 2021 AT 5:33 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This sounds like a crank sensor has failed. Here are a few guides that will help with this in figuring out what the issue is:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

https://youtu.be/dCjmRL3p4Cs

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

Below is the process from the manual that shows more info about this as well.

I would replace this and retest to see if it still cuts off. Let me know if you have questions. Thanks
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Sunday, March 28th, 2021 AT 5:55 PM
Tiny
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Only issue it has is will not start until engine cools down again then it will start. I can drive it all day long with no problems unless I shut it off. Then same thing will not start until engine cools.
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Thursday, April 8th, 2021 AT 10:03 AM
Tiny
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You are right. That doesn't sound like a crank sensor however, it may be running off the cam sensor and then when you cut it off, it starts back on the crank sensor.

Does it crank normally when it is hot and not starting?

If so, we need to check fuel pressure and for spark when this is happening. We need to find out which we don't have so we can track that down.
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Thursday, April 8th, 2021 AT 6:24 PM
Tiny
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Yes, it cranks normally when hot just will not start. That is the only issue. While it's running it is as smooth as can be. No other problems just will not start until it cools down. I've already replaced the cam sensor a while back and I have checked the fuel pump when the switch is turned on I can hear the fuel pump kick on. But like I said not starting when hot is the only issue. Other than that it runs and drives like a new car. It cranks when hot but it just won't start. It will crank when hot like normal it just will not start until engine cools down then it will start drive fine runs and drives smooth as can be as long as I don't shut it off but when I do I have to let it sit and cool down after it cools down it cranks up no problem starts. Until the next stop or leave it running until I get home so I'm not stranded. But it's exactly the same every time. Only issue is won't start when hot.
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Friday, April 9th, 2021 AT 9:39 AM
Tiny
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Okay. I understand. However, we need to find out what we do not have when trying to start the engine when hot. Just listening for the fuel pump is not going to be definitive because if the fuel pressure is low it will have trouble starting the engine especially when hot but it will be able to sustain the engine while it is running.

When the engine is hot, try using starter fluid in the intake and see if the engine starts.

If it doesn't then try performing a clear flood start by holding the accelerator to the floor and start the engine. If it starts while holding the accelerator to the floor then that means you have leaking injectors and it is flooding the engine. Holding your foot to the floor will cut the injectors off while cranking the engine.

Lastly we need to pull a spark plug when the engine is cranking and see if there is spark.

Let me know what you find with these three things as we need to start testing things to narrow it down. Thanks
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Saturday, April 10th, 2021 AT 7:20 PM

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