Ls1 shuts off after 20-30 seconds.

[radiowaves88]

OK, so here is the situation. I installed a LS1/4L60E from a 2000 Camaro into a 1946 Chevy pickup street rod project. I'm using a Painless Performance #60608 wiring harnass which incorporates the LS1/4L60E into a street rod chassis harness. The harness came with a free computer reflash which has already been done.
The engine started and ran fine, but after 20-30 seconds the engine shuts off. If I wait for a minute, it starts right up and runs for another 20-30 seconds. I did notice that when the engine begins to die, the fuel pump relay begins to kick on and off then goes off completely. I wired the fuel pump directly to the battery but it still does the same thing. I assume that when the fuel pump relay begins to kick on and off, I'm losing spark and or the fuel injectors also. Any ideas on where to look next?

[Cutlass]

The fuel pump relay should never click on and off while the engine is running. Wiring the fuel pump directly to the battery should have solved that problem but apparently it didn't.
The spark ignition system and fuel injectors are on a different relay and should not be affected by the fuel pump relay. The fuel pump relay should only be connected to the fuel pump.
You problem does sound exactly like its running out of fuel. Maybe there is something wrong with your fuel pump or something else inside the tank. Or maybe your fuel filter is bad, clogged?

[Raptor Avionics]

This may sound WAY left field but... I once had the exact same problem and it ended up being the chip in my key sending the signal through the steering coulmn harness (basicaly a security feature shutting off the motor). Being as you have done a swap I understand you may not even be dealing with this sort of set up. Just thought i would put it out there.

[radiowaves88]

I really don't think it's a fuel pump problem because when I wire the pump directly to the battery the pump continues to run and the pressure is good even when the engine shuts off.

[shady milkman]

This may sound WAY left field but... I once had the exact same problem and it ended up being the chip in my key sending the signal through the steering coulmn harness (basicaly a security feature shutting off the motor). Being as you have done a swap I understand you may not even be dealing with this sort of set up. Just thought i would put it out there.

vats shouldnt be on his old street rod....

[shady milkman]

I really don't think it's a fuel pump problem because when I wire the pump directly to the battery the pump continues to run and the pressure is good even when the engine shuts off.

i know this is incredibly simple ..but have you replaced the relay ?

[Raptor Avionics]

vats shouldnt be on his old street rod....

I agree, just throwing something out there that might have been overlooked

[20ws6speed01]

what is on that relay as pre diagram?? Is it ur Auto Shut Down relay??