Cranks but won't fire!
04-05-2011, 06:36 PM
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Cranks but won't fire! I have a 2000 trans am ws6 auto trans with an LS1. The car has been garaged, driven a few thousand miles a year, currently has 40k. Recently when attempting to start the engine, it would only crank but not fire. fuel pressure is fine. When the key is left in the on position for 10 minutes or so, and then turned to crank, it will fire and run normally instantly. Then if it is shut of, it will re-start anytime within about 15-30 minutes, otherwise the same problem occurs. This is not an intermittent problem. The car was always perfect and since this happened the first time is has never worked properly. This feels like an electronic fluke to me, has anyone run into this before and know of a possible solution? Thanks for any feedback.
04-05-2011, 07:28 PM
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Maybe a cam or crank sensor.
Googled it to see where the LS1 crank sensor was located and I found this; Also says the crank sensor will result in a no-start. If the ECU isn't seeing a cam or crank signal, it won't fire the plugs. It won't be able to time anything and doesn't "see" the engine cranking.
http://www.chevythunder.com/ls1_page_1.htm
Googled it to see where the LS1 crank sensor was located and I found this; Also says the crank sensor will result in a no-start. If the ECU isn't seeing a cam or crank signal, it won't fire the plugs. It won't be able to time anything and doesn't "see" the engine cranking.
http://www.chevythunder.com/ls1_page_1.htm
Camshaft sensor (CMP)
The camshaft sensor is a 1X pulse sensor which is synchronized to the #1 firing of the engine (Whether or not it is on its firing or exhaust stroke). The reluctor is located on the back of the camshaft. As the reluctor rotates, it interrupts the magnetic field produced by the sensor and the pcm interprets this as a pulse, after the signal is buffered by the internal circuitry of the CMP. The pcm uses this signal in conjunction with the crankshaft sensor (CKP) to determine the crank position and stroke. The pcm monitors this signal for any problems and sets the appropriate DTC (diagnostic trouble code) for loss or degraded signal. The pcm provides the +12V power, ground and signal return for the CMP.
A loss of this signal will result in longer starting times.
The camshaft sensor is a 1X pulse sensor which is synchronized to the #1 firing of the engine (Whether or not it is on its firing or exhaust stroke). The reluctor is located on the back of the camshaft. As the reluctor rotates, it interrupts the magnetic field produced by the sensor and the pcm interprets this as a pulse, after the signal is buffered by the internal circuitry of the CMP. The pcm uses this signal in conjunction with the crankshaft sensor (CKP) to determine the crank position and stroke. The pcm monitors this signal for any problems and sets the appropriate DTC (diagnostic trouble code) for loss or degraded signal. The pcm provides the +12V power, ground and signal return for the CMP.
A loss of this signal will result in longer starting times.
Last edited by bayer-z28; 04-05-2011 at 07:50 PM.
04-05-2011, 08:29 PM
#3
when you say your fuel pressure is good, what do you mean? just cause there is fuel to the rails doesn't mean it is good. my jeep had the same problem you are having and the problem was that i was only getting 15psi fuel pressure to my rails when the car was off, and it was cause the fuel was leaking back to the tank cause the fuel pressure regulator was bad, so what is your fuel pressure?
04-06-2011, 09:31 PM
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idk, this really sounds like a security problem to me. most gm vehicles, when tripping the security system, it takes 10 mins with key on to get another shot. is your security light flashing when trying to start it?
04-08-2011, 10:45 PM
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If you haven't found the problem, try this.
While turning the engine over look at the rmp tach and see if it move. If it don't move, it's the crank sensor.
I was changing my clutch in my 02 camaro. Went to start the car and it wouldn't start. Friend of mine told me about this trick and that is what it was.
Hope this is helpful
While turning the engine over look at the rmp tach and see if it move. If it don't move, it's the crank sensor.
I was changing my clutch in my 02 camaro. Went to start the car and it wouldn't start. Friend of mine told me about this trick and that is what it was.
Hope this is helpful
04-09-2011, 11:13 AM
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I had the same prob; switch out the starter and ignition relays; see this
https://ls1tech.com/forums/generatio...ns-aboard.html
https://ls1tech.com/forums/generatio...ns-aboard.html
