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L96 Cammed engine won't start hot?

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Old Aug 17, 2025 | 09:35 AM
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Default L96 Cammed engine won't start hot?

Hello All
I recently posted about this engine stumbling at low rpm loaded and I didn't mention the no start on hot restart. I thought this was two different issues but after thinking about it maybe they are related.
The engine starts cold with no issues. If I run a while then shut it off and try and restarting. It won't start. It cranks and cranks and maybe sputters a couple times but mostly no firing at all. If I quit cranking and try again it starts up normally. The best example is I run to the store and run it to grab something and come right back out and try to start. I now give it a short first crank and quit then it will usually fire up the second try. It seems if it sits for more than 20 minutes it starts with no issues. Last week it backfired through the intake on hot restart then ran normal. I'm starting to think the crank position sensor might be the issue. I have seen sensors act up when hot then work when cold before.


Last edited by Chad'sL96; Aug 17, 2025 at 11:00 AM.
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Old Aug 17, 2025 | 01:56 PM
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I had similar hot/warm start issues and the cause was leaking fuel injectors. Hook up a fuel pressure gauge and see if the shut down fuel pressure drops and how quickly. A pressure drop could be from the pump, but with warm start issue I would suspect the fuel injectors if you have a pressure drop. I would lose ~ 10lbs in a few minutes and down under 30 lbs within 6-7min. The car would usually start if I cracked the throttle a bit and I also once had a backfire through the intake like you mentioned.

It seems the fuel injectors started leaking after they were serviced although no report of that in the printout. I had that done while the motor was being rebuilt... attributed the issue to a cam change and needing a tune but nothing seemed to correct the issue (updated tune, fuel pump, spark plugs and wires).

Car fires right up now cold, warm or hot and fuel pressure drop is minimal after 10 minutes.

Last edited by vegas_ss; Aug 17, 2025 at 02:02 PM.
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Old Aug 18, 2025 | 08:21 AM
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if you prime it without cranking a few times will it start up first try? or no difference?
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Old Aug 19, 2025 | 07:02 AM
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I'll give that a try
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Old Aug 19, 2025 | 10:09 PM
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Originally Posted by vegas_ss
I had similar hot/warm start issues and the cause was leaking fuel injectors. Hook up a fuel pressure gauge and see if the shut down fuel pressure drops and how quickly. A pressure drop could be from the pump, but with warm start issue I would suspect the fuel injectors if you have a pressure drop. I would lose ~ 10lbs in a few minutes and down under 30 lbs within 6-7min. The car would usually start if I cracked the throttle a bit and I also once had a backfire through the intake like you mentioned.

It seems the fuel injectors started leaking after they were serviced although no report of that in the printout. I had that done while the motor was being rebuilt... attributed the issue to a cam change and needing a tune but nothing seemed to correct the issue (updated tune, fuel pump, spark plugs and wires).

Car fires right up now cold, warm or hot and fuel pressure drop is minimal after 10 minutes.
I had an identical issue as this. Was running some ebay injectors and the car was hard starting when warm/after it had run for almost any period of time. Bought a set of FIC injectors and the issue has gone away completely (It also runs better!)
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