ls3 525 stalling

[silvrgt3]

Hi,need help! 69 camaro crate ls3 525 driven 4k miles no problems then sudden shutdown with no codes,any ideas? thanks

[dhutton]

Hi,need help! 69 camaro crate ls3 525 driven 4k miles no problems then sudden shutdown with no codes,any ideas? thanks

That is a little light on details...

Did you verify good fuel pressure?

Don

[silvrgt3]

yes,good fuel pressure,installed new aeromotive 340 pump

[rickpaw]

Any blown fuses?

[Vegas69]

Start with the basics, fuel and spark and take it from there.

[cpd004]

A connector or wire may have worked it's way loose in the harness. What brand of harness are you using?

[silvrgt3]

gm,all fuses ok

[carkrazy1987]

is it currently a no start condition or start and runs, but will stall right away, or eventually?

[silvrgt3]

starts and runs perfectly for about 20 min then dies,sometimes starts after battery is disconnected then reconnected,but not always... is it possibly cpk sensor,but no codes

[Vegas69]

Uh, that would've been helpful up front. :lol:

[carkrazy1987]

ckp sensor usually wont cause it to shut off or not start. ls can start and run on cam sensor alone. have you watched the fuel pressure and get it to stall while watching? very tedious and time consuming to do. when it stalls does it just shut off like if the key was turned off, or stumble and shut off?

[cjsgarage]

ckp sensor usually wont cause it to shut off or not start. ls can start and run on cam sensor alone. have you watched the fuel pressure and get it to stall while watching? very tedious and time consuming to do. when it stalls does it just shut off like if the key was turned off, or stumble and shut off?



CKP is actually the ONLY sensor the ECM cannot make up a value for. Bad CKP means no start - no spark, no inj pulse.

But it also usually sets a code.


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[cjsgarage]

Have seen this issue with dirty MAF or with poor tune as well. The proportional and integral tables for idle airflow are what control the majority of stall saving.

Is it happening just sitting or is it coming to a stop: i.e. Rpms on their way down?

If it's just sitting, 99% of the problems we run into are a electrical problem. Usually a 12v supply dies off. Poor connection or overheated circuit breaker etc


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[silvrgt3]

bad fuel pump

[79 Camaro]

After it dies and you try to restart when you turn the key to run not start but run does the fuel pump run for a few seconds and then shut off?

On one of my LS swaps I had a similar problem. It ran great at first and then it would quit like turning off a light switch. I looked at everything. Thought it had to be a crank or cam sensor. I really hated the thought of pulling the header and starter to replace the crank sensor. I was poking around the wiring and then found the wire that goes from the constant 12 volt fuse to the ecm was loose in the connector and would heat up and loose connection. Fixed it and it's ran like top ever since.

If either your cam or crank sensor are faulty the engine will not run.I've never had one fail but not saying it couldn't.