LS1 run issue; i need help!
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Teching In
Joined: Feb 2012
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LS1 run issue; i need help! i need some advice, i installed a used 04 GTO LS1 into a new build 34 ford street rod. my engine supplier cut down the harness and reflashed the computer, i have an all new fuel system, walbro 255 pump in the tank, (PA-4 from tanksinc.com) -6 braided hose with russell fittings, corvette filter regulator, brand new battery. got it all wired up, fuel in the tank (2.5 gal) 02 sensors are connected but not yet hard mounted into the exhaust, all the other sensors, MAF, TPS, air temp, crank, cam are connected. when I turn the key, the engine fires (2 seconds) then stops. pump shuts off. fuel pressure is 54psi at prime and when the pump is running stays there. (at the pump and the fuel rail) when the pump shuts off it bleeds off to 50 psi then leaks down from there. i understand the engine requires 56-58 psi but it should still be able to start and run with 54 psi right? i'm still looking into why i only have 54 psi not the 65 psi at the pump as is advertised. i checked the pump assembly installation it's fine, i increased the power lead from 12 gage to 10 gage. the only code the computer shows is for fuel tank pressure low, which is an emission code.P0452 Fuel Tank Pressure Sensor Circuit Low Voltage, this will not nor ever was intended to have a pressurized fuel system that new vehicles are required to have. anyway, it should still start and at least idle. i don't know what else to check. i can only think that the computer is not happy and shuts it off, i'm at a loss. any suggestions? these engines can't be that sensitive. 
Last edited by rakrick; May 31, 2017 at 10:22 AM. Reason: added trouble code
Teching In
Joined: Apr 2016
Posts: 13
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From: Gainesville, FL
i need some advice, i installed a used 04 GTO LS1 into a new build 34 ford street rod. my engine supplier cut down the harness and reflashed the computer, i have an all new fuel system, walbro 255 pump in the tank, (PA-4 from tanksinc.com) -6 braided hose with russell fittings, corvette filter regulator, brand new battery. got it all wired up, fuel in the tank (2.5 gal) 02 sensors are connected but not yet hard mounted into the exhaust, all the other sensors, MAF, TPS, air temp, crank, cam are connected. when I turn the key, the engine fires (2 seconds) then stops. pump shuts off. fuel pressure is 54psi at prime and when the pump is running stays there. (at the pump and the fuel rail) when the pump shuts off it bleeds off to 50 psi then leaks down from there. i understand the engine requires 56-58 psi but it should still be able to start and run with 54 psi right? i'm still looking into why i only have 54 psi not the 65 psi at the pump as is advertised. i checked the pump assembly installation it's fine, i increased the power lead from 12 gage to 10 gage. the only code the computer shows is for fuel tank pressure low, which is an emission code.P0452 Fuel Tank Pressure Sensor Circuit Low Voltage, this will not nor ever was intended to have a pressurized fuel system that new vehicles are required to have. anyway, it should still start and at least idle. i don't know what else to check. i can only think that the computer is not happy and shuts it off, i'm at a loss. any suggestions? these engines can't be that sensitive.
if problem persists then read codes again
Thread Starter
Teching In
Joined: Feb 2012
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I've been told VATS has been disabled. i cleared the codes with the scanner.
i'm beginning to think that there is something in the code that is looking for a signal from a sensor that's not there and it shuts off the fuel pump. but i don't know because i don't know squat about programming the ECM.
i'm beginning to think that there is something in the code that is looking for a signal from a sensor that's not there and it shuts off the fuel pump. but i don't know because i don't know squat about programming the ECM.
Teching In
Joined: Apr 2016
Posts: 13
Likes: 0
From: Gainesville, FL
I've been told VATS has been disabled. i cleared the codes with the scanner.
i'm beginning to think that there is something in the code that is looking for a signal from a sensor that's not there and it shuts off the fuel pump. but i don't know because i don't know squat about programming the ECM.
i'm beginning to think that there is something in the code that is looking for a signal from a sensor that's not there and it shuts off the fuel pump. but i don't know because i don't know squat about programming the ECM.
this will reset the ECM
Thread Starter
Teching In
Joined: Feb 2012
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quick update. i pulled the PCM, sent it out to be re-flashed. i was told it was just re-flashed with the same program that was in it, only this time it fired up and kept running. that being said, i don't know what the real issue was, which being a control enthusiast is concerning in it's own right.
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" i'm still looking into why i only have 54 psi not the 65 psi at the pump as is advertised."
Not unusual to find the Vette reg/filter has some psi variation.
They are not rated at 65psi in that filter/reg.
We use WIX units, and find "most" are at 4 bar.
Not unusual to find the Vette reg/filter has some psi variation.
They are not rated at 65psi in that filter/reg.
We use WIX units, and find "most" are at 4 bar.
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