I have owned a '98, & 2002, & currently 2003 blazer with 4.3 Vortec engines. Love the engine! Hard to kill em! Anybody have any idea why '98 had spider injection and '02 & '003 have TBI?? Seems a step backward to me!!

 

There`s a spider under the throttle body

 

The only difference between the fuel systems used in your '98 and that used in your '02 & '03 trucks is in the location of the electronic injectors in the spiders themselves. The '98 had the SCFI spider where the injectors are located in the center body and they feed pressure activated poppet nozzles that are located down in the individual intake runners. Somewhere in the '02 model year, they switched over to the MFI spider which has the electronic injectors mounted at the ends of the tubes right in each of the intake runners. This gets rid of the poppet nozzles that liked to gum up with age and not give a consistent spray pattern.

The upper intake plenum (plastic piece below the throttle body) & throttle body itself are the same for all 1996 thru end of production 4.3L engines used in the s-series trucks.

 

O I C ! Havent gotten that far into it yet!

 

[QUOTE=newguy;687952]There`s a spider under the throttle body[/QUOTE Makes sense! Thanks!