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'04 GTP owners

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imported_Ron Vogel

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Hey guys, thought I'd pass this along for those of you with fueling problems. I have a 2000 GTP that I put an IC on. I picked up a set of '04 rails to modify so I had a cleaner factory look. I lopped of the ends of each rail to braze on an inverted flare fitting. Inside the rail is an insert, much like a flattened tube. It is held in by a couple of tension springs. With it in there, it poses quite a restriction to the injector feeds (in fact it sits about a 1/32" right above the injector feed). It slides right out, and with it out the rail is much more free flowing. My best guess is that it's in there to reduce pulsations in the rail. It may be why so many '04s run out of injector, with so few mods.
 

toastyj

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This is interesting Ron. Send me an email with some further info if you can.
I am modding my car fast (really fast if you look at mods to miles ratio).
Send me an email with some pix or more info on this if you can, I'd appreciate it...
enough to buy you some beers on our first race day or meet together!!
lol
Thanks, man.
 

beyerch

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Originally posted by Ron Vogel@Aug 14 2004, 10:13 PM
Hey guys, thought I'd pass this along for those of you with fueling problems. I have a 2000 GTP that I put an IC on. I picked up a set of '04 rails to modify so I had a cleaner factory look. I lopped of the ends of each rail to braze on an inverted flare fitting. Inside the rail is an insert, much like a flattened tube. It is held in by a couple of tension springs. With it in there, it poses quite a restriction to the injector feeds (in fact it sits about a 1/32" right above the injector feed). It slides right out, and with it out the rail is much more free flowing. My best guess is that it's in there to reduce pulsations in the rail. It may be why so many '04s run out of injector, with so few mods.
As someone else stated on the clubgp the real reason is that the regulator is inside the pump and does not adjustic like the old style one. Because of that, you run out of injector quicker than you would on our model of cars (i.e. not stepping up of fuel pressure).

It seems GM is going to this type of design and i'm sure to them there's a good reason, but not for us ! :)

The item you located is surely for reducing the pulsations which are not really a problem until you go larger than a 42.5 injector.

If there were only a way to control that darn fuel pump though for increased pressure ..... :ph34r: :p B)
 
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imported_Ron Vogel

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A lot of '04 guys are considering an FMU or something. I can't quite understand (other than being cheap) why GM would go to a returnless system, and not boost referenced. Seems it would be hard to tune a base fuel pressure of 60psi, when atmospheric pressure of the cylinder goes up. That in theory means that availible fuel delivery is reduced when the engine needs it most. BTW, if you saw what they call a "pulsation dampner", you'd laugh. It probably works somewhat, but it's really just a flattened tube with crimped ends laying inside the rail. If you had a '04 rail off the car and shook it, it would most likely rattle, it's not in there very tight.
 

toastyj

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It probably works on the same premise as an air foil. Straightens the fluid as it flows to create less drag (air is a fluid btw as it flows to fill the shape of it's container, Earth Science101, Waubonsee CC! LOL).. Anyway, Im sure it's cheap, but all it has to do is restrict oscillating flow to the point it runs smoothly.
At least I would imagine.
 
I

imported_Ron Vogel

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Originally posted by toastyj@Aug 16 2004, 02:34 PM
It probably works on the same premise as an air foil. Straightens the fluid as it flows to create less drag (air is a fluid btw as it flows to fill the shape of it's container, Earth Science101, Waubonsee CC! LOL).. Anyway, Im sure it's cheap, but all it has to do is restrict oscillating flow to the point it runs smoothly.
At least I would imagine.
If you haven't been following it, check out the thread in the '04 section "critical fueling info". Looks like the stock pump recieves PWM signals to maintain fuel flow, there is some good info in the thread about a lot of variables.
 

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