Max pump output pressure is within specs, but it's very low, typical with Airtex pumps. A good pump will hit 100psi with no problem. Your leakdown (in the pump) is borderline, also typical with Airtex, and will get worse, guaranteed.

The excessive leakdown issue is not the pump. Removing the plenum will reveal external leaks only, ie: fuel pressure regulator, spider fuel lines, or injector housing leaks. Those items must be isolated from the pump using two shut off valves to determine which one, or more, things are leaking. Possible leaks that are not visible even with the plenum removed are: fuel pressure regulator bypassing internally, any one or more of the poppet valves or injectors.

 

Ok. SO I am going to remove the top and see if I can see anything visually. The dual shut off thing may be something I need some help with if I can't see anything by eye. Regardless, it doesnt sound like a regulator is too pricey, so I will replace regardless. Not sure how much a spider or injectors cost. Any ideas--ballpark? If its not too much I might as well do it all while I am in there. Might take me till Tuesday to finish the teardown. The Mrs. has a few things she needs done before tomorrow and I got a long day Monday. Thanks for your guidance and check back on me please!

 

Regulator is a possibility although, it's not a common problem on CSFI systems. If leakdown is still excessive after replacing it, the only other thing is the spider/injector assembly and it's available as an upgrade including a new regulator! It modifies the system by eliminating the poppet valves and relocating the injectors to the intake ports. Ebay and Amazon have them, if you look, you can find them for under $200 and it's money well spent.

 

Ok I got it all apart. It was much easier and faster than I thought reading on these threads. As afar as what I see, the top of the intake, under the spider, is black from the front to about the last fourth closest to the rear, which is spotless clean. The runners going to 5 and 6 are also pretty clean as opposed to the others that are black. The engine has 185k on it so I expected it to be dirty. The pressure regulator has an out let on the back pointing downwards and if I had to guess, it appears to have been leaking/spraying gas in the aft area near the 5 and 6 runners. Is that normal? the injector assy is dirty but there doesnt appear to be any damage to the spider. I would hate to change the regulator and have it do no good at this point. Is the new assy Captain was talking about avail at GM or NAPA or??? I wanna get this thing done!

 

Pic??

 

 

The regulator should not leak fuel. If it does, replace it. The fitting pointing downward on the regulator is open to the back side of the diaphragm. Manifold vacuum is what controls the regulator, ie, high vacuum=low fuel pressure...low vacuum= high fuel pressure. No vacuum hose is necessary because the entire plenum is exposed to manifold vacuum. The tube at the front of the lower manifold that sticks up into the plenum is from the EGR valve. When the EGR valve opens, exhaust fills the entire plenum, that's why it's black... normal. Where it's "washed" is where the problem is... fuel leak. Looks like it's been leaking for a while.

GM dealers carry the assembly, but be prepared to take out a second mortgage on your house. A cheaper option is an auto parts store, they carry them too. A third option is Amazon & Ebay, they're close to $100 cheaper than the auto parts stores. http://www.amazon.com/gp/offer-listi...&condition=new Don't forget the plenum gasket.

 

Got the new improved injector/spider/regulator assy and installed it. Wasn't happy the parts house neglected to tell me it requires a new bracket...sold sperately...for another 30 bucks...that is only at one parts house...many miles away. Anyway got that and although I am not fond of the install, the new spider is much less flexible than the old and more difficult to route without kinking the spider tubes themselves I finally got it in. New plenum gasket and cleaned the throttle body real good. Off to brunch this am but will finish later to see if it all works. Would have had it done but for the bracket issue. Will update later.

 

Got it put back together and it started right up. Drove it about ten miles and so far so good. Runs great and so far no SES light. Cross my fingers but so far it looks look to go. I need to put some miles on it and get it inspected for license plate before it throws the light again for something new! ALthough I have replaced everything almost already..... I expect at least 30mpg now! Ok I will settle for 17.

 

What brand name was the injector assembly?