First off iI'm wana say i am a new member and this is my first post. Hello everyone. So I blew up my LM7 5.3 in my 03 GMC with a return style fuel rail. I already bought an L33 non flexfuel motor with the injectors and fuel rail on it, I will not have it till next week sometime. Is this going to be a direct swap for the fuel systems? I herd 04 and up motors had a returnless fuel system. Could I use my existing fuel rail with the L33 injectors because aren't the l33 injectors bigger? I believe the fuel calibration codes are the same, so working pressure shouldn't change. Any input would be good. Oh and am I going to have any other issues with this swap?

 

Welcome. Should be a direct swap with no issues at all and your fuel system should carry over as well with no issues. Now the L33 is the "HO" version of the 5.3 and is a little higher in compression which is why they use a littler bigger injector but shouldn't be more then what your stockers can handle but you can use the ones that come with it really doesn't matter. Do you have your truck tuned or have a local tuner? If so just get your tuner to over look the tune but really it's a direct swap so shouldn't have to change much if anything.

 

thanks. I'm hoping to use the L33 injectors just because they were made for that motor app. so i will probably just swap the fuel rails. I do not have a tuner but i just have a superchips flashpaq. After everything is said and done i was thinking about getting a tune.

 

Youll have to get it tuned for the injectors and throw the super chip in the trash

 

If your going to leave it stock just swap longblocks and use all the original to the truck dressings.

 

i thought the knock sensors were on the side of the block on the l33 and the cam sensor is on the front cover. so you will have to extend the harness out and have the computer tuned to make the knock sensors some what work. they work off a different frequency than the 03 stuff.

 

L33 is still 24x reluctor?

 

I've got a L33 block from a 05 Z71.... Knock sensors are in the valley and cam sensor is in the rear. Should still be 24x

 

All correct.