i tell you.. i really don't know how will i squeeze myself out of this one..
a bought a complete set of seals and what not, everything is new in this tbi except the injectors, i don't know what else can i do..
buying another diaphragm or another set of seals won't help me find out where's that leak is coming from.. and i doubt it will fix it.
the thing is if i google the diaphragm i can see the two layers that looked suspicious to you, so why should we assume that there's something wrong with it?
plus as far as my intelligence gets me i can see only one way to assemble everything so I'm not wrong there. so what else is there? could it be that the new diaphragm is defected?
the only thing that looks strange to me that i haven't mentioned yet is that through the little window on the bell housing i can see the spring right? well that spring is wet, i mean fuel wet - should it be?

You should not have fuel on the top side of the diaphragm. That there tells me that there is a leak inside.

what do you mean when you say the top side?
the window i'm, talking about is visible in the yellow circle on the picture, i can see fuel there.. i guess i would call it the bottom part of the diaphragm

Sorry, yes, the bottom side. Still, I don't think that spring should be wet. To me that says that the diaphragm and/or gasket is leaking in that area.

I can't find a good schematic of the throttle body disassembled in any of the references I have available to me right now, but I have the FSM for the '90 R/V series trucks at home which should cover this in detail.

any info you can post for me will help in some way.
as far as the spring - if we can determine for sure that it shouldn't have fuel on it or in it's area then i guess that's the problem for sure.
i'll wait for any schematics you can find,
thanks!

well.. i've decided to take a final l;ook before buying a new rebuild kit.
the diaphragm looks a bit beaten up but i've discovered something more interesting - the fuel pressure regulator cover, the bell housing wasn't flat on his edges.
it seemed like it can't apply even pressure onto the edges of the diaphragm. so i straighten the edges out and reassembled the entire thing.
on the first engine start, fuel squirted all over the place and i immediately turned the engine of in order to locate the source of the leak.
surprisingly the edges of the diaphragm that sticks out in the picture felt dry but the fuel meter body seal was soaking wet and the spring was wet as well.
we've already determined that the spring can't be wet under any circumstances - so that brings us back to a diaphragm that can't seal properly.
but it gets better... after failing to find the leak i've started the engine in order to see the squirting again - but this time it ran beautifully. everything looked nice and dry...
i did some homework about the operations that goes through the system - i do got a better understanding about the whole procedure, but honestly i can't set my mind on how and why the leakage came only on the first ignition and stopped.

These are the best I could come up with short of scanning them in. Cell phone takes some pretty decent pictures though! :)

http://i11.photobucket.com/albums/a1...1775622481.jpghttp://i11.photobucket.com/albums/a1...1775678523.jpghttp://i11.photobucket.com/albums/a1...1775497388.jpg

None of my references really have an exploded view showing the fuel pressure regulator taken apart, but the diaphragm should be above the can that the spring sits in.

i just wanted to thank you for your help, and for the references you posted for me.
i bought a new rebuild kit today and replaced only the diaphragm, so far everything looks good.
I'velearned a lot about the T.B.I system in the last few days, so i suppose it was worth it :) even though the problem was a pain! - i guess the diaphragm wasn't 100% sealed.
the new one seems to doing it's job. thanks again!

Glad you got it all fixed up!