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Engine cutting out on idle

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Old May 9, 2006 | 03:20 AM
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Default Engine cutting out on idle

I have recently got my LS6 up and running in a Cobra Kit car.

The engine runs for about 30 seconds to a minute, then the fuel pump sounds like it is running out of fuel (which it isn't as there is plenty of furl in the tank) the fuel pressure drops and the engine cuts out. It will restart after a bit of churning, but will do the same. Also if I get on the throttle, I can keep it running.

Any ideas?
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Old May 9, 2006 | 08:26 AM
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strange!!!! check the voltage at the pump as the car is about to die. Maybe the pump is not getting enough power.....
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Old May 9, 2006 | 08:32 AM
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Is your fuel tank vented?
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Old May 9, 2006 | 10:35 AM
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Whats your charge rate at?
-Alex
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Old May 9, 2006 | 11:38 AM
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The tank is vented

I will check the voltage at the pump, but the pump actually speeds up as if it is not drawing in any fuel, before the fuel pressure drops and the engine dies.

Does anyone think that the fuel relief valve could cause this problem, if it is not working properly. The fuel pressure gauge is reading quite high when the pump is buzzing, and then dies down to 58psi, which is when the engine cuts out.
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Old May 9, 2006 | 06:13 PM
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probably a stupid question but, with the ls1 set up, isn't the fuel tank supposed to be pressurized by the return line or something? wouldn't that be why the smog guy pressure tests the fuel cap to make sure it is holding? could it have anything to do with this problem. is the tank sumped for the kit car? is there anyway that something is clogging the fuel inlet in the tank?
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Old May 9, 2006 | 06:21 PM
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The tank is not pressurized by the return line. The tank should not be pressurized to any large extent, mabey 2-3 psi, but that is not for the fuel pressure, that is because of the emissions. The tight emissions standards mean that we cannot leave the tank vented to atmosphere because of evaporation, which is why they test the gas cap, they want to make sure it is not leaking fuel vapors, it has nothing to do with the engine running properly.
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Old May 9, 2006 | 07:01 PM
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Originally Posted by G-Body
The tank is not pressurized by the return line. The tank should not be pressurized to any large extent, mabey 2-3 psi, but that is not for the fuel pressure, that is because of the emissions. The tight emissions standards mean that we cannot leave the tank vented to atmosphere because of evaporation, which is why they test the gas cap, they want to make sure it is not leaking fuel vapors, it has nothing to do with the engine running properly.
thank you for clearing that up it makes sense now. i didn't even think of that. i thought it might have something to do with how it ran but guess not.
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Old May 22, 2006 | 04:57 AM
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I found the problem was a blockage on the return pipe to the the tank, which was stopping the fuel pressure regulator working properly.

Thanks for all the help
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