New design of intake and fuel delivery for 99?

lunytnz · October 3, 2014

A mechanic mentioned that he thought there was a new, updated design for the intake for the 99 Vortec. He described the fuel pressure regulator as being at the top of the 'tunnel' and it could leak. I didn't find any info on a new design in a search of the forum. Anyone know if it exists?

Thanks much!

grampadirt · October 3, 2014

I wonder if he's referring to the MPFI upgrade?

02suburbanZ71 · October 4, 2014

Well pre 99 was the 5.7 which was spider injection. I think??? Not fuel injected like 99+. Is that what we're talking about, I'm confused

lunytnz · October 4, 2014

From what the mechanic described, it sounds like he thought it had the spider injection. But, mine is a 99 with the 5.7, so that may mean it is the multi-port injection. I tried to look it up in the FSM I have, but couldn't find the answer, for sure. Maybe it already *has* the upgrade???

02suburbanZ71 · October 4, 2014

I honestly don't know. Thats a tough one

lunytnz · October 22, 2014

So, what is the MPFI upgrade and where can I learn more about that?

Is there any easy way to tell if what I have in the rig is the spider injection? I heard there was an upgrade/new design of the spider injection system... anyone have details on that or where I can find out more?

Thanks!

lunytnz · January 11, 2015

In case this helps others... I found that there IS an upgrade/new design of the spider injection system for my engine. Apparently, the biggest difference is that it moves the injector/sprayers to the end of the spider tubes, rather than at the beginning of each tube (where they attach to the fuel pressure regulator (FPR)). This upgraded part is apparently only available through the dealer. It comes as an assembly, which includes the FPR. You only have to take off the upper-half of the intake manifold to replace it.

I did talk with someone about upgrading to a true multi-port injection system, but the word was that would involve changing out the computer/ECM, as well.

We found evidence of fuel leaking from the FPR, which was just being wasted. So, in the few weeks since upgrading the spider injection, my gas mileage is up about 10-20% (around 14-15 now, where it was in the 12-13 range before). I haven't really noticed any difference in performance.