Had my new MPFI fuel spider put on and my '01 Jimmy runs so much better. No more gas in the oil and my mileage has increased from 200/tank to 275/tank. If anyone needs the part no, its available by searching the forums, and make sure you buy from GMpartsdirect.com -much cheaper!

 

Lets rephrase that a bit... Everyone that is having trouble with sticking poppet nozzles and/or leaking injectors should replace their SCFI spider with the updated MFI spider. An updated MFI spider has no benefits over a properly working SCFI spider. And a SCFI spider can be kept in tip top condition by running injector cleaner through the system at every oil change.

So people that have trucks that are running correctly, don't go out and dump the $200-300 on the updated spider! There are many, MANY checks you have to go through first before you should consider dumping that kind of money into it.

 

Maybe you're right, but to those like me who pick up one of these trucks with over 100k miles that wasn't taken care of properly and the SCFI spider is leaking, I'd save yourself trouble and replace it with the updated unit. I will definitely be running injector cleaner through my system every 5000 miles to keep it that way. I should have taken pics of the old spider, it was nasty looking [:@]

 

I still have my old spider sitting in a box in my garage (need to clean it out!). I know what you mean, I'm just trying to limit the needless replacement.

There is also another down side to the MFI setup that won't affect most. If anyone is planning on forced induction or some other power adder requiring higher fuel flow rates, the SCFI spider can flow more lb/hr than the updated MFI setup. The S10 guys found this out with some of their setups running dangerously lean, going static on the injectors even with elevated fuel pressures. Just an aside.

But the MFI spider does offer the removal of the problematic poppet nozzles which if left leaking will result in main electronic injector failure at some point down the line. The MFI spider is also cheaper than the SCFI spider in the vew places where I checked!

So if you've run down through the checks and verified that your spider is defective and do not plan on running over ~300chp, the MFI spider will be the better choice over the stock SCFI spider and can be replaced without any modifications. You just have to heed the installation procedure (especially for the #3 injector).

 

I've also heard (not confirmed) that the individual injectors on the MPFI setup cannot be replacedor upgraded, both individually and complete, without replacing the whole spider. Any truth to this?

 

I do believe that is true. I never could find a PN for the injector and tube to the metering body for the MFI injector. I think it is mainly to keep people from putting in one or more MFI injectors into a SCFI spider. An MFI injector is going to have a different IPW than a SCFI injector and they cannot be mixed.

 

Sorry to bring back an old thread... i'm trying to find what year the MFI replaced the SCFI system. I've searched and from what I can tell my 99 has teh SCFI but am curious what year they switched?

 

Mid-02 was the first year for the MFI spider.