FrankZ

Donor rig is an 03 Tahoe with Flex Fuel capability, and I'd like to retain that if possible. So here goes:

I received the FCS when I got my engine, harness, and PCM but it was only connected via the harness. Which tube is the inlet?

I've had the rear O2 sensors deleted from my PCM, do I need to use the After-Cat O2 sensors when running E85?

G-Body

iTrader: (4)

You do not need the rear o2`s. I will check on my brothers swap tomorrow to see which is the inlet.

nmcgrawj

Where was the FCS when u pulled it from the tahoe?

FrankZ

I didn't pull the engine, the JY did. They delivered everything stacked on a pallet.

nmcgrawj

Cool. So did u just give them a list of stuff u wanted/needed?

G-Body

iTrader: (4)

Dang, forgot all about checking. FCS was under the drivers seat area on a crossmember.

nmcgrawj

Thanks for that info. Is it just T'd into the fuel line from the tank?

G-Body

iTrader: (4)

The pressure line from the fuel tank flows through it.

FrankZ

Okay, but still I need to know which tube is the inlet and which is the outlet.

Thanks.

deuce4935

iTrader: (2)

I just Googled this topic and it seems that either fitting can be used as the feed and the return. This is because the sensor is able to determine what kind of fuel is passing thru. I'm assuming that GM had some extra fittings in place on the donor vehicle that would've come in hand for the swap if you wanted a factory looking install.

Nashty

iTrader: (7)

Aside from this sensor and the required tuning for it, what other changes are needed for a flex fuel vehicle? I'd personally LOVE to do this to my transplant.

G-Body

iTrader: (4)

The sensor is hooked up from GM so that the nipple closest to the electrical connection goes to the fuel pump. The further smaller diameter connection is connected to the fuel rail.

FrankZ

Perfect! That's exactly what I needed to know.

Thanks!!

G-Body

iTrader: (4)

Depends on what PCM you have. If you have the blue/red PCM you cant do it. If you have the newer green/blue PCM you can probably add a FCS and reflash with a flex fuel tune. The easiest way to do it is to just start out with a flex fuel motor.

FrankZ

FYI,
My 03 Flex Fuel Motor has the blue-green connectors

dgcustomz

iTrader: (127)

I just did a swap on a 77 c10 and the engine was out of an 03 tahoe with the red and blue pcm and had the flex fuel system. I had the flex fuel tune removed and also trashed the fcs.

G-Body

iTrader: (4)

Guess it is possible to have the red/blue PCM with flex fuel.