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!

 

Greetings,
A newbie non-mechanic looking at buying a 2002 GMC Jimmy with 177,000 KM on it.
It has a 4.3 litre engine. I had a 1997 Safari van with the 4.3 litre engine AND the fuel spider began to fail...I was told the spider was plastic and that later years of the 4.3 had a metal spider instead.
Any experience with this detail? This may be the deal breaker as I do not want another plastic spider issue.
HELP!
Thanks,
Dave

 

By now it would be rare to see a 1996-2001 with the old style spider still on it. The new MPFI spider is the upgrade. Yeah, lots of plastic in either one. Not metal vs plastic.

 

My 2000 still has the original spider in it. I've been wanting to swap to MPFI for a number of years, and I probably do it sooner rather than later. But, the thing still runs great. Rather than replace it, though, I throw in the 5.3 that I've had for a few years in the Blazer.

 

A cool thing with the upgraded spider version is that you can change individual injectors if needed.

 

If you are interested in the upgrade injectors or their parts, you might look to see about their availability. I suspect they are getting harder to find. I was able to score a NOS upgraded injector to install when I replaced my LIM gaskets many years ago.