School me on "Flex Fuel"

[sandking]

Yes I am new here , but as some of you may know, I will be installing a 2008 5.3 into my '72 Blazer. I will be picking up the motor this weekend. I am not sure if it was a flex fuel motor or not (how do I tell?)(dont have the VIN untill this weekend). My questions is, will this have any affect on my conversion? Anything special might need to be done? Not sure yet wether or not any of this applies, but worse case scenario, what do I need if anything?

[1slos10]

Here you go..

[sandking]

So, a 2008 5.3 did not have flex fuel injectors?

[1slos10]

I would think it was optioned for 08, and the injector plug should be the same.

[GasGuzzler]

Never seen the middle style on a stock truck. 3800's have those though.

[sandking]

........So what make a motor a flex fuel motor? Is the ECM and the harness the same as a non flex fuel? Anything else that may be different?

[lechez71]

hey sandking the 5.3L motor that im going to get is also a flex fuel motor, but its missing parts on the intake so if i swap out the intake, harness and the pcm from a 99 model will it work.

[sandking]

I guess my question is this, if the engine is a flex fuel, cant I treat it as a normal engine? I just want to gas it up and go. I would rather not swap anything, but if the install and tune will be a PITA, I will. I just dont know the difference between the two.

[farmtruc]

There's no difference, just plug and go!

The tune in the pcm can go either way, so just running gas is fine.
Since you're probably not using the rest of the fuel lines, tank and sensor, don't even worry about if it's flex fuel or not, just treat it as a regular non flex engine.
If it is, it came with larger than standard injectors, so that's good.
Just make sure you have 58psi or so of fuel pressure.

later,
allen

[sandking]

Perfect!! Thats the answer I needed. Thanks!!