Flex fuel injectors
10-22-2013, 06:08 AM
#1
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Flex fuel injectors I am doing an LQ9 swap into a Chevelle. The LQ9 is complete with the intake but I also have an intake off of a 5.3 that has the flex fuel injectors. Will the flex fuel injectors work in the LQ9 intake/fuel rail? The 5.3 intake is kinda messed up but could be repaired with some epoxy I guess. I would rather use the LQ9 if I could. Also wondering do the flex fuel vehicles run at 58 psi also? I saw on LT1Swap.com that the flex fuel injectors were rated at 33 pounds per hour @ 50 psi which leads me to believe that is the rail pressure gm used for flex fuel. I havent been able to find much info on this subject and any help would be appreciated. I am wanting to send my ecm off to get it flashed pretty soon.
10-23-2013, 01:28 PM
#2
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I am doing an LQ9 swap into a Chevelle. The LQ9 is complete with the intake but I also have an intake off of a 5.3 that has the flex fuel injectors. Will the flex fuel injectors work in the LQ9 intake/fuel rail? The 5.3 intake is kinda messed up but could be repaired with some epoxy I guess. I would rather use the LQ9 if I could. Also wondering do the flex fuel vehicles run at 58 psi also? I saw on LT1Swap.com that the flex fuel injectors were rated at 33 pounds per hour @ 50 psi which leads me to believe that is the rail pressure gm used for flex fuel. I havent been able to find much info on this subject and any help would be appreciated. I am wanting to send my ecm off to get it flashed pretty soon.
https://ls1tech.com/forums/fueling-i...ruck-guys.html
10-24-2013, 08:19 AM
#3
To answer your question, the flex fuel injectors used on the 5.3L are longer, and use a different electrical connector than those in the 6.0L. If you used the 5.3L fuel rail & injectors, it should install on the 6.0L intake.
The flex fuel rail 01 to 04 with rail mounted regulator did run at a slightly lower fuel pressure.
The 8.1L truck injectors mentioned are drop in, same height, and electrical connector.
The fuel pressure specs are straight out of GM Service Information online service manuals.
"1999-2003 4.8, 5.3, 6.0 all had a fuel rail with 3/8" supply line and a 5/16" return line. The fuel pressure regulator is on the fuel rail, and has a vacuum line to the intake manifold. In 2004, All engines went to a single 3/8" supply line, with NO RETURN LINE (returnless) except 5.3L L59 Flex Fuel vehicles. For 2004, Flex fuel engines KEPT the return line, BUT used a fuel pressure regulator with a lower pressure ratting. 2005 5.3L L59 Flex Fuel engines switched to a single 3/8" supply with NO RETURN line in 2005. Non flex fuel engines, fuel pressure spec is 55 to 62 psi with vacuum line disconnected, fuel pump running. 5.3L Flex Fuel engine 2004 and back, 48-54 psi with vacuum line disconnected, fuel pump running. 2005+ with returnless fuel rail all shared same fuel pressure spec, 55-62 psi. There is no vacuum reference on these, so fuel pressure should remain constant under all operating conditions. The computer is programmed differently for fuel flow rate depending on type of fuel rail. This is important to know when having a PCM programmed."
The flex fuel rail 01 to 04 with rail mounted regulator did run at a slightly lower fuel pressure.
The 8.1L truck injectors mentioned are drop in, same height, and electrical connector.
The fuel pressure specs are straight out of GM Service Information online service manuals.
"1999-2003 4.8, 5.3, 6.0 all had a fuel rail with 3/8" supply line and a 5/16" return line. The fuel pressure regulator is on the fuel rail, and has a vacuum line to the intake manifold. In 2004, All engines went to a single 3/8" supply line, with NO RETURN LINE (returnless) except 5.3L L59 Flex Fuel vehicles. For 2004, Flex fuel engines KEPT the return line, BUT used a fuel pressure regulator with a lower pressure ratting. 2005 5.3L L59 Flex Fuel engines switched to a single 3/8" supply with NO RETURN line in 2005. Non flex fuel engines, fuel pressure spec is 55 to 62 psi with vacuum line disconnected, fuel pump running. 5.3L Flex Fuel engine 2004 and back, 48-54 psi with vacuum line disconnected, fuel pump running. 2005+ with returnless fuel rail all shared same fuel pressure spec, 55-62 psi. There is no vacuum reference on these, so fuel pressure should remain constant under all operating conditions. The computer is programmed differently for fuel flow rate depending on type of fuel rail. This is important to know when having a PCM programmed."
10-24-2013, 07:31 PM
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Thank you for the reply! I actually swapped the fuel rails and injectors over to the 6.0 today and plan to go that route. My harness and computer are off of the flex fuel engine anyway.
