i went and draw this out, i just wanna make sure if this is correct when plumbing the SFMU w/o the stock FPR on a 97-99 model. here goes:



please let me know if this is correct...

By looking at the drawing, i dont *think its correct. Basically, you want a fuel line coming from the fuel rail test port, going into the SFMU "in" port. Then, you will run a return fuel line back to the tank from the "out" port on the SFMU. You are getting high pressure fuel into the fuel rail from the stock feed line going into the rail. You use the test port to output fuel into and through the SFMU, then heading back to the tank.

alright see if this is right now, i'm a little confused how this is suppose to regulate the furl going into the fuel rail...

alright see if this is right now, i'm a little confused how this is suppose to regulate the fuel going into the fuel rail...

From what I understand, the FPR just causes all the fuel in the rail to get 'backed up', thus increasing fuel pressure.

My guess is that somehow, the SFMU has some type of valve that closes a little once it sees boost, and causes fuel to get backed up...........again, this is just my guess.

From what people have told me your diagram is right. I plan on installing mine sometime soon, it should be interesting.

I can't see the first one but the second is correct.

sweet! thanks fellas for the feedback, i'm also hooking this up as well next week, it's time to ditch the regular FMU already!

The SFMU controlls fuel pressure by shutting off, or letting more fuel and pressure be "bled" off. YOu get high pressure fuel flow all the time up to the fuel rail, the SFMU just bleeds all the uneeded fuel pressure out back to the tank. When under boost, the SFMU will close off more of the bled fuel pressure, and thus your pressure has no where to go but out the injectors, equaling more fuel. When not under boost, the SFMU is bleeding and recirculating A LOT of fuel. The SFMU is just a simple fuel valve bleeder. Fuel doesnt actually go into the SFMU and to the fuel rail, it comes FROM the fuel rail, and then back to the tank. Hopefully that made some sense :)

Nice job on the second *correct* diagram Darkreality :thumbsup. That should definitely be put into the "Things we've seen before" thread although it only covers the late model fuel system. I own a 96 GS which is a late model system but I believe the early models have the stock FPR on the fuel rail so this diagram doesn't apply to them. All in all, still good to have as a reference as many people ask.

One more thing, you may want to consider putting a tee in the line running from the fuel rail to the "IN" port of the Vortech fuel regulator. The tee will allow you to have a test port to set your idle as well as for a max fuel pressure under boost. Once you are done with testing, the test port could be simply plugged. This will make it way easier instead of removing a line from the vortech or from the fuel rail. I know I have used this test port numerous times in adjusting pressures for different temperatures (I run a higher idle fuel pressure in the winter). Here is a picture of what I am talking about and some information regarding additional parts (if interested):

Test port.




Additional Parts:
- 3 foot 1/4" fuel hose
- 1/4 NPT Tee with 3 1/4" NPT to 1/4" Hose Barb Fittings
- 1/4 NPT Pipe Plug (this came with the Hahn Kit)
- The Vortech SFMU has -6 JIC fittings so you will either need to buy two conversion fittings (one for the IN and one for the OUT on the vortech) that has -6 JIC Female to NPT (The -6 JIC will go into the vortech). I did not buy the fittings as I had access to a machine shop. I simply removed the flare from one side of the -6 JIC fitting to make it flat, drilled it out to slightly smaller than 1/4", and then threaded the inside of the fitting to 1/4" NPT. This allowed me to attached 1/4" NPT 1/4" Hose Barb fittings.


Installation:

After running the hose from the fuel rail I attached the other end of the 1/4" fuel hose to the 1/4" Hose barb fitting on the tee. I then ran the other end of the tee to the IN on the Vortech SFMU. You now have one more port on tee to use to connect to the fuel pressure gauge from Hahn. You can then run the fuel pressure gauge under the hood an onto the front windshield for testing (just latch the hood, do not close it as it will pinch the fuel hose). Here is a picture to clear it up. You will also have to run the out of the Vortech SFMU to your return line to the tank. Remember to use teflon paste fo a leak free seal and to plug the tee once testing is complete.


Just an idea,
Kurt

If I'm just replacing my Cartech with the S-FMU will it pretty much just be a straight out swap or is there other things that will need to be changed? How much time would you guys think I'll be looking at to do this?

sorry, but i need to bring this thread back for a moment, i justt bought the SFMU today, and i need the above question answered. because by the look of the cartech install, looks like it would be a direct replacement, however i just need to know what disk/ring to use for me setup: stage 1 turbo w/ stock injectors, and walbro 255lph HP pump. thanks

or if its as easy as that diagram above, should be nice install.

largest disk, hardest spring I believe.

alright cool, so just install the largest disk, with the black hard spring, and follow the directions above right. thanks for the quick response, im gonna install it tomorrow.

#eidt#: oh, by the way what ring to use with this?

thanks man, yeah i now understand the process of the regulator, as for the tee, i knew about it, i just forgot to add it to the drawing, inline the tee with the B&M fuel pressure guage i have and line it to the SFMU. well atleast this finally sums this up. i hope this is a lot of help for everyone. :thumbsup

Very helpful ... great drawing. I will doing this same install next week myself. Thanks for asking the question. This should definitely posted up as link somewhere on the board.

http://www.2gnt.com/nuke/modules.php?name=Sections&op=viewarticle&artid=82