Hey Guys,

I am trying to figure out the easiest way to identify a flex fuel 5.3 motor. The junk yard has a bunch of motors, but I have no idea what model number or cast number to look for. Can anyone help me out? I would also like to find a flex fuel motor that uses the throttle by wire because I plan on hooking this motor up to a built 700R4.

Thanks for the help.

David

 

On the ones I've seen they've got a sort of square tubing looking stainless steel fuel rails. The non flex fuel engines have the traditional black plastic or metal, not sure which, round tube looking fuel rails. Other then that, the 8th digit of the VIN will be a Z but if the engine has been pulled then the vin isn't much use to you.

 

Yes, most of the motors have already been pulled out of the trucks. I was trying to find some type of number on the engine itself for identifying a flex fuel motor. thanks for the VIN Z info.

 

Yea its nice to be absolutely sure. Like I said though all the Z motors that I've seen installed in the vehicles have had the square stainless steer fuel rails. I believe this is due to the corrosive nature of E85.

 

Flex or non flex has nothing to do with round plastic fuel rails vs metal fuel rails, there are flex fuel truck available with both style fuel rail. The metal fuel rails basically mean its a 2007+ engine. The 1999-2007 engines have round plastic fuel rails.

IF your looking for a flex fuel motor without a VIN, look for

A) The black round fuel rails, on the mounting tab there will be two small ribs. Also if you unbolt the tab the bolt hole will have a brass insert.

B) The injectors are longer than the injectors on non flex 5.3L