does not want to start, sometimes
Thread Starter
6th Gear
Joined: Apr 2024
Posts: 6
Likes: 2
From: Idaho
does not want to start, sometimes
Hi - I'm new the Corvette and have a problem I hope you can help me with.
I have an LS1 motor in my 2004 Corvette. The engine is stock except cold air intake, headers and a mild Crower cam. The issue I have is the car will start and then die.
If I disconnect the battery and let the car sit for several hours, I can get it to start and run. If I then turn the car off, I can get 1 or 2 more starts and it runs fine. After that, it will run for 5-10 seconds, then die. After that, it fires and immediately dies. After that, it turns over but will not start.
Here is what I have tried:
Fuel pressure is always between 58 & 62 lbs normal pressure - pump runs exactly how it should.
Confirmed all grounds are good and all connections are clean.
PCM has the battery connections and ignition connection correct. It has voltage when it should have voltage.
Confirmed VAT system is not the issue per the dealer
There are no pending or stored codes.
I have injector Diode I can plug into the injector wire, I have tried all 8, when it does not want to run it will flash a couple of times then stop. The car will run on brake cleaner or ether.
Help !!!
I have an LS1 motor in my 2004 Corvette. The engine is stock except cold air intake, headers and a mild Crower cam. The issue I have is the car will start and then die.
If I disconnect the battery and let the car sit for several hours, I can get it to start and run. If I then turn the car off, I can get 1 or 2 more starts and it runs fine. After that, it will run for 5-10 seconds, then die. After that, it fires and immediately dies. After that, it turns over but will not start.
Here is what I have tried:
Fuel pressure is always between 58 & 62 lbs normal pressure - pump runs exactly how it should.
Confirmed all grounds are good and all connections are clean.
PCM has the battery connections and ignition connection correct. It has voltage when it should have voltage.
Confirmed VAT system is not the issue per the dealer
There are no pending or stored codes.
I have injector Diode I can plug into the injector wire, I have tried all 8, when it does not want to run it will flash a couple of times then stop. The car will run on brake cleaner or ether.
Help !!!
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,615
Likes: 4,062
From: Cape Coral, Florida
If the car runs on an alternative fuel you have a fuel delivery issue…don’t know what this means…”I have injector Diode I can plug into the injector” ???…what is this ??
.
Joined: Apr 2013
Posts: 5,034
Likes: 1,156
From: Oregon
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
Thread Starter
6th Gear
Joined: Apr 2024
Posts: 6
Likes: 2
From: Idaho
its like a small test lite that plugs into the injector wire. You can unplug the injector wire plug this little test lite in and it will blink if the computer is sending an impulse to the injector....
does that help?
does that help?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,615
Likes: 4,062
From: Cape Coral, Florida
Never heard a noid light described that way !!…actually the noid light is not the best test of injector function since you are only seeing if the injector is powered and the PCM is grounding it…scoping injector current is way better…usually around 1 amp.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,615
Likes: 4,062
From: Cape Coral, Florida
Yes, but noid light is usually what it is referred to…you have a fuel delivery issue so I’d look at fuel pressure when it dies out.
Thread Starter
6th Gear
Joined: Apr 2024
Posts: 6
Likes: 2
From: Idaho
when it dies its about 60PSI give or take a lbs or 2. this is from a mechanical gauge hooked to the fuel rail. I also tested the ohms in the injectors they are all at 12.3 or 12.4 ohms
The part I don't get is the noid lights up or blinks a couple of times and then stops, even if you keep cranking the motor. If its doing that, then there is no fuel delivery?
why does it stop pulsing? Is there something else in the computer that can shut it off?
I have been trying to work this problem out for about 6 months now...... just about ready to put a for sale sign in it.....
thanks for any help you can give.
have a great day
The part I don't get is the noid lights up or blinks a couple of times and then stops, even if you keep cranking the motor. If its doing that, then there is no fuel delivery?
why does it stop pulsing? Is there something else in the computer that can shut it off?
I have been trying to work this problem out for about 6 months now...... just about ready to put a for sale sign in it.....
thanks for any help you can give.
have a great day
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Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,615
Likes: 4,062
From: Cape Coral, Florida
Maybe it’s a bad crank sensor…with a bad sensor you will not have injector pulse AND spark…if the car becomes a “crank no start” look at the Tach…if it doesn’t move while cranking it may be the crank sensor….a scope is the best way to see the signal.
Melting Slicks
Joined: Sep 2008
Posts: 3,138
Likes: 802
From: Espanola New Mexico
could be a bad crank position sensor or a bad cam position sensor as both work together to provide the pulses for the injectors and Ignition coils, I would inspect the wires that connect to both sensors.
Melting Slicks
Joined: Sep 2008
Posts: 3,138
Likes: 802
From: Espanola New Mexico
To clarify on my last post, the cam and crank position sensors provide output pulses that the pcm uses to generate output ground closures for the injectors and Ignition coils. Have you removed and inspected the connectors at the pcm, make sure the negative battery cable is disconnected.
Thread Starter
6th Gear
Joined: Apr 2024
Posts: 6
Likes: 2
From: Idaho
update
I have replaced the coils, computer, injectors, fuel regulator fuel filter and main engine wiring harness. I have spark. When you turn on the key the pump primes to 60 psi. During cranking it drops to 50 to 55 psi and bounces back and forth, but will not start. Can a fuel pump put out pressure but no volume?
Thanks for the help
Thanks for the help
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,615
Likes: 4,062
From: Cape Coral, Florida
I have replaced the coils, computer, injectors, fuel regulator fuel filter and main engine wiring harness. I have spark. When you turn on the key the pump primes to 60 psi. During cranking it drops to 50 to 55 psi and bounces back and forth, but will not start. Can a fuel pump put out pressure but no volume?
Thanks for the help
Thanks for the help
