Flex Fuel conversion for a 2004 Silverado 5.3

Dany Bravo · March 17, 2022

Looking to Convert a Non-Flex fuel 5.3 Vortec to Flex Fuel. Just wondering what was needed to do the conversion. Is it worth it? Do I need a bigger pump? I have a set of 42lb flex fuel injectors for the truck. Do I need to change fuel lines, mess with the harness at all, Change the OS on my pcm, etc. All help is appreciated. I know there is a bunch of write ups about this topic but every one says something different.

CamGTP · March 17, 2022

The stock fuel pump should be fine. You just need larger than stock injectors and the wiring to make the sensor function. The fuel lines can stay the same.

What I don't know off the top of my head is what operating system you would need to use. The Suburbans and Tahoe's and some Silverado/Sierra's were flex fuel vehicles with factory 33lb/hr injectors but I don't know the OS numbers.

You'd need to look in the HP Tuners Tune Repository if you own HP Tuners to see what is available for 2004 computers.

Dany Bravo · April 25, 2022

On 3/17/2022 at 6:45 PM, CamGTP said:

The stock fuel pump should be fine. You just need larger than stock injectors and the wiring to make the sensor function. The fuel lines can stay the same.

What I don't know off the top of my head is what operating system you would need to use. The Suburban's and Tahoe's and some Silverado/Sierra's were flex fuel vehicles with factory 33lb/hr injectors but I don't know the OS numbers.

You'd need to look in the HP Tuners Tune Repository if you own HP Tuners to see what is available for 2004 computers.

Any Idea what size fitting I would need to connect the sensor to the fuel rail? Sorry for the super late reply, forgot this site existed and work has been driving me crazy.

CamGTP · April 25, 2022

Same as the factory lines, 3/8th.

You just have to create a loop in the system from the feed line into the sensor, out of the sensor and back into the fuel rail.

Dany Bravo · April 25, 2022

1 minute ago, CamGTP said:

Same as the factory lines, 3/8th.

You just have to create a loop in the system from the feed line into the sensor, out of the sensor and back into the fuel rail.

Got it. Appreciate it boss man.