No start when hot
Thread Starter
Teching In
Joined: May 2025
Posts: 4
Likes: 1
From: NY
No start when hot (5.7 lt1 m6) I can start up my car just fine when its cold. If I shut off my car or stall after driving for any longer than 15 min it wont start again until it cools down. I replaced the spark plugs, drained the radiator and replaced the battery. please help
edit- also replaced the starter, same problem
edit- also replaced the starter, same problem
Last edited by SAINTZ; Oct 4, 2025 at 08:44 PM. Reason: added info
TECH Fanatic
Joined: Oct 2022
Posts: 1,776
Likes: 627
From: Louisiana
Be more descriptive, does it turn over like its trying to crank but possible not getting fuel?
or does it click like its a battery issue?
Are the lights and interior gauges still working?
It takes details to get a response on here.
or does it click like its a battery issue?
Are the lights and interior gauges still working?
It takes details to get a response on here.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
Likes: 112
Confirming fuel and spark is basic diagnosis. Hook a FP gauge up to confirm if it has enough "pressure". It should immediately go to about 43 PSI when priming then drop to about 38PSI after prime
One common no start when engine is at temp but starts when cold is bad IAC
One common no start when engine is at temp but starts when cold is bad IAC
Might be a long shot, but the injectors might be leaking badly so the engine gets flooded when it's hot and it sits for a while. A fuel pressure gauge, as other have mentioned, will help you. For a simple test, heat the engine up, shut it down, let it soak for 15 minutes or so, and then try to start it with "clear flood" mode engaged. Very easy to get into that mode. Put the pedal to the floor and crank it.
What year is your car?
Did this develop all at once or has it gotten worse over time?
I hear off your description it will crank but no start? Look at the tach needle and see if you see it twitching while it's cranking when it's acting up. If it's not twitching you have a no spark situation.
But gotta start at the basics sufficient fuel pressure, spark, and a noid light to check for injector operation. Ideally a scanner to look at data is the most important number one. But most dont have it or know good from bad when scanning the data list.
Did this develop all at once or has it gotten worse over time?
I hear off your description it will crank but no start? Look at the tach needle and see if you see it twitching while it's cranking when it's acting up. If it's not twitching you have a no spark situation.
But gotta start at the basics sufficient fuel pressure, spark, and a noid light to check for injector operation. Ideally a scanner to look at data is the most important number one. But most dont have it or know good from bad when scanning the data list.
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