The Vortec intake has a fuel pressure regulator and injectors inside the intake manifold. There are two fuel lines going into the fuel pressure regulator in manifold. Six injector lines come off the regulator and go into little holes in the lower intake manifold. It looks like a spider because of the six little injector lines and the fuel pressure regulator in the middle. I've changed the spider in my wife's '93 Jimmy. It's not a terribly difficult job.

 

thanks! exactly what i was thinking it was...just wanted to clarify..not to hijack thread but my 91 seems to be having the same issue mentioned + a rough idle after its warmed up. and it also is eating gas like crazy not sure if thats just how these trucks are.... or if something is wrong

 

It's very likely that you're having the same problem with the leaky spider injector. The best way to test it is to get a fuel pressure gauge and attach it on the test port at the back of the intake manifold. Run the truck for a couple minutes and then shut it off. The gauge should read 55-60psi while it's running and the pressure should maintain for at least five minutes. If the pressure drops right away then something is leaking. If the gauge test indicates a leak you can follow further diagnostic procedures to determine whether the fuel pressure regulator or the fuel supply and return lines (often called a "nut kit") are the source of the leak.

 

Ive heard that when you change the oil you can smell it to see if it reeks of gas smell.

My junk yard spider injector seems to be holding up fine for now, though im not sure how well its flowing being how old it is. If I ever needed to buy a new one, I would probably buy one from here: Fuel Injector Service

From what I've read on this site it comes with an adapter to run the newer fuel pressure regulators. But if money is an issue you can always look for a pick a part, pull a part, or pick n pull in your area and get the whole assembly for somewhere around $20. When you pop open the intake at the wrecking yard youll be hoping to find one that looks black all over inside the intake because that means its less likely there were any fuel leaks.

You can always take your upper intake manifold off, and while the top of it is off with the injector exposed, have somebody turn the key to the on position and see if there are any leaks when they do it, you can also look to see how clean it is inside your intake, that is also a sign of a leak.

 

A 91 has TBI injection, not CPI. Completely different system...

 

hello jake. have you found the fix, for your vortec problem. the rough idle. i have the same dang issue.

lee anne, i have the same problem, i need help

 

Yes, as I stated toward the end of page 2. After swapping out the spider injector my vehicle is now running like a champ. The miss that it had is completely gone, I will say that it still seems like it is missing some power, but it does idle/run nice and smooth now.

I am going to check all the remaining valves and sensors on the vehicle that I have not yet inspected or tested when I get a little more free time but its running pretty good now.