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I'm having a HORRIBLE time trying to get accurate characterization data for a set of injectors I purchased second hand. Best I know is they came off of a 2002 Flex Fuel Tahoe / L59. I have multiple pressure regulators for different pressures. Currently running 58 PSI, but is beside the point.
Baseline tunes I pull for flex fuel trucks are at 33#/hr. Marketing data online shows 30#/hr. Then there's newer flex injectors at 58PSI which flow 35.4#/hr. I haven't a clue what these things actually are I need accurate 100% reliable injector characterization for a 2002 Flex Fuel Tahoe AND what regulator is spec'd for that 2002 L59. It seems there's so much information online you just end up with what you search for. Additionally, parts catalogs don't distinguish between flex fuel pressure regulators L59 and regular pump gas LM7. I know the connector is a EV6 connector.
Can somebody tell me at what regulator is spec'd for a 2002 Flex Fuel Tahoe? And any additional info on the injector setup?
Thanks!
I bought adapters from ICT billet. The injectors are 100% the dimension of right hand side. The connector is that one as well. I've been running them for a few years now... However, my tune is getting more nuanced. Hired a professional tuner to help me and I thing we isolated some of my issues to be due to inaccurate injector characterization.
Open the Holley Terminator X engine parameter section on the terminator X program.
Flex fuel inj 125580426 is listed in the drop down.
Look at a tune with them in it.
Oh wow that helps. Although it seems to provide different characterization from what I'm pulling in various GM baselines characterizations form HP Tuners repository? I'm seeing it has characterized the injectors at a higher PSI.
Any idea what factory pressure regulator / PSI is for a 2002 L59 Flex Fuel 5.3L engine?
Last edited by weinerschizel; Dec 14, 2025 at 06:11 PM.
Pretty sure the older flex fuel Tahoes (2002) ran at 50 psi, which is why the flow rate is shown as being lower in the calibration. I don't know what year they went back up to 58 psi but that's also when you see the corresponding flow rate increase, I'm 99% sure it's the same injector but it's been a long time since I've even dealt with these.
You will find the most accurate data for those injectors in the later trucks/SUVs to use for 58 psi base pressure, and it will be complete and accurate data unlike what the Term X shows for them. Either way the data is so close it's not going to account for much more than a couple of percent in fuel trims one way or another.
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Flex Fuel Injector Characterization 
