Gen III Flex fuel Write-up
07-03-2014, 12:44 AM
#1
Gen III Flex fuel Write-up Ive already had alot of people asking me about this setup and a few wanting a write up so i will go into as best detail i can about this.
This will allow you to run any fuel and not worry about the ethanol content.
I did this flex fuel on my 1999 silverado. Basically the same as any 99-02 fbody. I did upgrade to the 0411 pcm which is common pcm for 99-02 camaros. The 99 truck pcms were known for problems which is why i switched.
I had already updated my injectors to 50 lbs flex fuel injectors. The part number for anyone wanting to use that is 12613412. They came off of 2010-2014 trucks with a 6.0. I am however still using the stock pump and havent had any problems.
Hardware-
1. You will need to tap into the fuel line somewhere. It doesn't matter whether it be the feed or return. Feed made more sense to me as the fuel will be analyzed before the motor sees it.
Since the sensor i was using had the same inlet and outlet size as my fuel line i used Russel fitting 644123, which is a 3/8 to stock fuel line fitting. I then used a -6 to -6 fitting then another fuel line fitting quick connect fitting.
Sidenote- For a fbody, The fittings may very but will generally be the same. there might even be more room on a camaro that what i had to work with.
2. Flex fuel sensor- As far as flex fuel sensors go, you have a few options.
13577429- This is the one used and is small and fits nicely. the price is nice also
13577394- Longer fuel leads but the same internally.
13577379- Same as above but has very short leads and i dont think the quick connect fittings would work.
Gm makes a very expensive one also, but dont waste your money as that one is the same as the ones above
3. Harness- I used 13352241 and hacked the end off i didnt need...
4. You will also need some wire and a pcm lead connector. I had a few from a pcm bench harness i made but if you don't have them the internet does and they are cheap. They are just Micro-Pack 100W 1.0 Terminals. Search that and find some!
5- HPtuners to Load the New OS onto your pcm.
12216125 - That is the os for the 02 Tahoe Flex Fuel operating system.
Wiring-
I am going to include the diagrams for the connectors and pcm to make it a little easier to see what im talking about. But the sensor just needs a ground, Which i ran to the nearest ground on my truck which was conveniently about 4 inches away but any ground will do.
Next is a switched power source, I looked on the diagram to see what the actual sensor is to be powered by. Pin 19 is an ignition power and is what the sensor should be powered by on the tahoe. Any switched 12v source will do if you cant find the 19 pin on the pcm. It was a pink wire on my truck.
The last on the flex fuel sensor is the actual wire which tells the pcm what content its seeing. This is pin 56 on the pcm.
Thats basically all you need to run a Flex fuel Pcm in a gen 3 vehicle. Now on to pictures of the install and diagrams.
Here is the sensor with my connector and the an fittings that attach to the fuel line.
Pin 19 is seen here as ignition voltage.
Here is the power for the sensor, You can see it runs off of the ignition voltage from pin 19.
Flex fuel sensor connector view. As you can see its only 3 wires.
Everything installed and wired. I ran out of wire wrap so it looks ugly now but im going to get more this week. And also dont mind the dirty and crazy injector harness.... But its in and runs amazing!
Overall this was very worth it. Being able to run any fuel is very cool.
This will allow you to run any fuel and not worry about the ethanol content.
I did this flex fuel on my 1999 silverado. Basically the same as any 99-02 fbody. I did upgrade to the 0411 pcm which is common pcm for 99-02 camaros. The 99 truck pcms were known for problems which is why i switched.
I had already updated my injectors to 50 lbs flex fuel injectors. The part number for anyone wanting to use that is 12613412. They came off of 2010-2014 trucks with a 6.0. I am however still using the stock pump and havent had any problems.
Hardware-
1. You will need to tap into the fuel line somewhere. It doesn't matter whether it be the feed or return. Feed made more sense to me as the fuel will be analyzed before the motor sees it.
Since the sensor i was using had the same inlet and outlet size as my fuel line i used Russel fitting 644123, which is a 3/8 to stock fuel line fitting. I then used a -6 to -6 fitting then another fuel line fitting quick connect fitting.
Sidenote- For a fbody, The fittings may very but will generally be the same. there might even be more room on a camaro that what i had to work with.
2. Flex fuel sensor- As far as flex fuel sensors go, you have a few options.
13577429- This is the one used and is small and fits nicely. the price is nice also
13577394- Longer fuel leads but the same internally.
13577379- Same as above but has very short leads and i dont think the quick connect fittings would work.
Gm makes a very expensive one also, but dont waste your money as that one is the same as the ones above
3. Harness- I used 13352241 and hacked the end off i didnt need...
4. You will also need some wire and a pcm lead connector. I had a few from a pcm bench harness i made but if you don't have them the internet does and they are cheap. They are just Micro-Pack 100W 1.0 Terminals. Search that and find some!
5- HPtuners to Load the New OS onto your pcm.
12216125 - That is the os for the 02 Tahoe Flex Fuel operating system.
Wiring-
I am going to include the diagrams for the connectors and pcm to make it a little easier to see what im talking about. But the sensor just needs a ground, Which i ran to the nearest ground on my truck which was conveniently about 4 inches away but any ground will do.
Next is a switched power source, I looked on the diagram to see what the actual sensor is to be powered by. Pin 19 is an ignition power and is what the sensor should be powered by on the tahoe. Any switched 12v source will do if you cant find the 19 pin on the pcm. It was a pink wire on my truck.
The last on the flex fuel sensor is the actual wire which tells the pcm what content its seeing. This is pin 56 on the pcm.
Thats basically all you need to run a Flex fuel Pcm in a gen 3 vehicle. Now on to pictures of the install and diagrams.
Here is the sensor with my connector and the an fittings that attach to the fuel line.
Pin 19 is seen here as ignition voltage.
Here is the power for the sensor, You can see it runs off of the ignition voltage from pin 19.
Flex fuel sensor connector view. As you can see its only 3 wires.
Everything installed and wired. I ran out of wire wrap so it looks ugly now but im going to get more this week. And also dont mind the dirty and crazy injector harness.... But its in and runs amazing!
Overall this was very worth it. Being able to run any fuel is very cool.
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nickp (07-30-2020)
03-02-2015, 08:13 AM
#4
Just read thru your thread...thanks a million for the information. This will make life so much more convenient. Any feedback on how the car has been running with the setup since the install?
04-18-2015, 06:55 PM
#6
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Ok well this intrigued me so I decided to dive in and try this. I have the OS swapped to the 02 suburban flex fuel in my truck 411 type pcm , added the flex fuel sensor to pin 56 (early S10 aluminum style), and the tune changed with HP tuners. I am having some weird problems though, the alcohol content in the HP scanner is only showing whatever I set my default value to. It also doesn't appear to be changing the fuel trims to match the commanded afr. I am not getting any engine codes related to a faulty sensor so I am assuming its fine. Any advice would be appreciated. A working calibration file might be helpful to look at in case I am missing something. I have also attached mine if someone wants to take a look.
04-20-2015, 05:16 AM
#7
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Ok well this intrigued me so I decided to dive in and try this. I have the OS swapped to the 02 suburban flex fuel in my truck 411 type pcm , added the flex fuel sensor to pin 56 (early S10 aluminum style), and the tune changed with HP tuners. I am having some weird problems though, the alcohol content in the HP scanner is only showing whatever I set my default value to. It also doesn't appear to be changing the fuel trims to match the commanded afr. I am not getting any engine codes related to a faulty sensor so I am assuming its fine. Any advice would be appreciated. A working calibration file might be helpful to look at in case I am missing something. I have also attached mine if someone wants to take a look.
There is a lot of misinformation out there and I found some regarding the wiring of the sensor. The pinout I was referring to had pins A & C wrong. I swapped them around and everything works great.
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From my understanding, the 05 express van pcm is the one to have, but if you have the older setup, you will need to move a few wires around in it to work. I am also in the exact same boat, and am trying to figure this out as well.
My current setup has the Blue/Red with a 01 truck OS. I will also be going to the 3bar OS from the 05 Express Van with Flex Fuel.
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