I have a 1999 blazer lt 4x4 4door. I'm a little confused on the spider injector. Everytime I do a search for my year and specifications, I get a different one then the one I have.

my question, is there a difference in the two other then the injectors. Can I use either or? Or only the one that matches mine?

The one that keeps coming up

The one i have, note the injector tips.

 

Since yours is a different style than mine, I don't know what is right.

But, have you tried looking on rock auto, seeing what is specified for your year model? Then, if you want, search for that part number on Amazon

 

I've replaced it with one last summer from the scrap yard, just went with one that matched, but curiouser on the other one...

 

You can use either. The top one is the upgraded version CSFI to MPFI conversion kit. Got mine from eBay for $226. There are other vendors that make this upgrade but I stayed with AC Delco as I didn't want to cut corners when rebuilding my engine. This upgraded version eliminates the original poppet nozzles shown in the bottom photo. These have a tendency to get clogged and aren't as efficient. The upgraded version has the injectors at the end of the tube. It's a straight conversion and no calibrations needed. It's just a little tight with the stuff on the ends. One bit of advice if you go with the upgrade, make sure you have each of the injector tubes exactly how you want them before you seat them in the holes. They are almost impossible to get back out. I made this mistake on one of them and had to buy the new plastic tip on the end as I mangled it getting it out. Also, read the instructions as there is a specific way to route each of the tubes before seating. There are a ton of YouTube videos on this conversion. Hope this helps.

 

Thanks on that! Answers my question excaly... have you notice any differences?

 

You want the MPFI upgrade for sure. There are other manufacturers as well as AC Delco. Shop around. Try Rock Auto, etc.

 

I installed the AC-Delco 2173028 MPFI injector in my 1999 in 2017. I got it at Rock Auto for about $220.00.

I can't say I noticed much difference but I had figured that since I was doing the LIM gaskets I might as well upgrade the injectors in anticipation of the originals likely failing someday. I had also decided I wanted to keep the truck for at least 5 more years which made it easier to spend the money.

 

Can't say that I have noticed a difference but the upgrade is going to perform better in the long run. The old poppet style has one main injector that pressurizes the 6 tubes in the intake manifold to spray fuel. The poppet style is bad about leaking pressure regulators, improper spray patterns and they can develop a tendency to stick open or clog. The upgraded MPFI has electronic injectors at the end of each fuel tube and is just a better design than the original. I didn't notice better mileage or HP but some people say they have. I upgraded because my Blazer is a project and I plan on keeping it for a long time so I want to try to avoid any of the problems with the original CSFI.

 

Your statements above may be confusing the CPI spider with the 96+ SCFI spider. The CPI spider only has 1 electronic injector (2 wires to control it) that feeds 6 lines & poppet nozzles and is VERY prone to leaks in either the regulator or the fuel lines internal to the intake.

The SCFI (or CSFI depending on what manual/page you are reading from) spider has 6 individual electronic injectors (12 wires total in the connector even though the +12V feeds are all on the same circuit) located in the centralized injector body that feed the 6 individual lines & pressure actuated poppet nozzles that are located down in the intake runners. The poppet nozzles themselves are prone to leaking & spray pattern abnormalities as they age (as you stated) which is what most often leads to decreased performance and "failure" of this style system. Regulator problems in the SCFI/MPFI systems are very few and far between from my experience here.

The upgraded MPFI spider simply moves the electronic injectors out to end of the tubes replacing this often problematic-with-age poppet nozzle arrangement and is a bolt in replacement for the stock 96 thru mid-02 SCFI spider. GM also has an updated bracket that the housing snaps into, but the only difference is added clearance in a few locations to limit the possibility of a line rubbing against the bracket & failing. So long as proper care is taken to orient the lines and/or clearance your stock SCFI bracket prior to buttoning everything back up, changing out the bracket isn't necessary.

 

I'm very thankful for your post concerning the injection spider assembly & that there's an upgrade for it ! I actually was thinking of purchasing 1 for the future , perhaps you could post the part no's for the assembly & bracket ? I'd really appreciate it !