Things the vehicle has
30# Accel Injectors
Stage 2 HRC
Walbro 255

Poll question: Which SFMU set up do you prefer??

Poll result (3 votes) 2.72 disk/ring combo and Long Spring (3 votes) Vote 2.72 disk/ring combo and Short Spring (0 votes) Vote (0 votes) Vote (0 votes) Vote (0 votes) Vote (0 votes) Vote

i dont have 30#'s but i would be using the dark spring.

I am running that disc with the dark spring and 42#ers

i just finally got my car working like it should be and im using 30# and the largest disk (no ring) and short spring...the 2.72 disk and short or long spring was crap.... by the way, when you say dark spring, is that the long or short one?? mine are only long and short, no color change....
doug

From my experiences, when running larger than stock injectors and lowered fuel pressures, you have to use the longer, silver spring in the SFMU, in order to get the fuel pressure low enough..The shorter dark spring lets you run a higher fuel pressure(so you dont bottom out the adjustment screw) to the stock 50-55 psi.. This was from my own experience though..

i think you got that backwords...adjusting the screw out lowers the pressure right? therefore using the smaller spring, it would lower your fuel pressure.... is that right, loosen screw to lower pressure, tighten to higher pressure?
doug

i thought it was the dark spring that allowed the lower pressures, but i dont remember.

but exactly what matt said, i couldnt get my fuel pressures low enough without the correct spring.

Originally posted by CarbonFiberRST
I am running that disc with the dark spring and 42#ers

are u using the safc with that combo(42lb and sfmu)?..

3.62 disc, ~20psi idle pressure, dampen the fuel curve with a bleed valve.

Tightening the top screw raises your pressure, and loosening lowers it. When I first got the SFMU, it comes factory with the longer silver spring, and I remembered I had problems getting the idle fuel pressure up to 55 psi, as the screw was almost bottomed out. So I had to swap that spring with the shorter, harder dark spring.. Then when i went to the 30lb injectors, I had to swap out that spring with the longer silver, factory one, as the dark spring would not let me get the pressure low enough(22 psi at idle). Who knows, maybe my SFMU was just jacked haha..

Originally posted by XtremeRS
When I first got the SFMU, it comes factory with the longer silver spring, and I remembered I had problems getting the idle fuel pressure up to 55 psi, as the screw was almost bottomed out. So I had to swap that spring with the shorter, harder dark spring.. Then when i went to the 30lb injectors, I had to swap out that spring with the longer silver, factory one, as the dark spring would not let me get the pressure low enough(22 psi at idle).

Just curious, when you switched out your springs, were you using the same 3.72 disk that was in the SFMU when you got it from Vortech or did you switch out to the 2.72 disk/ring combo and use the silver spring???

I used the largest disk with either setup..I just used the bleed valve to lower the boosted fuel pressure a bit when i used the 30lb injects..This way with the bleed valve, i knew i had plenty of fuel pressure left in case i needed to raise the boosted fuel pressure some. But if you dont use the bleed valve, the 2.72 disk/ring should be perfect for the 30lbers.

2.72 Disk/ Dark Spring/ Bleed Valve, 30lb injectors..running about a 6-7:1 ratio with a few turns of the bleed valve.

Alvin

hmm right now I'm using the lowest pressure spring it silver in color I ordered the two other ones I"m missing but the one I'm using gives me rediculously low FP, soemtimes my car won't even start. So i wound up bottomming out the FP screw can't even use that lock nut anymore. I got it up to around 22-24psi.

I'm gonna put that dark spring everyone is talking about so I can get more travel on the screw when i get it. ^_^

i'm using the 2.72 disk/ring combo with dark spring,400cc injectors,idel fp is 15-17(still rich but no black smoke)..car idels good but i get the cell p0172..

I hate to bring back old threads, but I figured since I was doing some searching I would just post it here...

OK so I just finally got my FP guage hooded up in my car...the one in the engine bay has been hooked up. OK I am running the SFMU with the silver spring/largest disk/30# with the 255 fp.

My FP at idle is 30 and at WOT it went up to about 90. Does this sound a bit too rich? I think its pretty rich, but my car idles great. If I lower it with the top valve, my idle will be shit. Should I try a lower disk or get a bleeder valve at this point?

Oh yah, what place sells the bleeder valve for a good low price?

Probably too rich, I used the dark spring and 2.72 disc/ring with 30#.
Now I have 440s and still use the 2.72 with a couple of turns on the bleed valve to get it around 11:1 at WOT @ 14psi. I dunno my fuel pressure... Wideband...

I was riding to work today and it climbs and hits 90 and holds strong at WOT. I will try switching to the dark/short spring and the 2.72 disk after work to see if that helps. If I have a idle of 30 my WOT should be around what?...60 to 65? I also have a set of 440's that need to go in, but I was going to wait and install them while I was doing my rebuild on the motor and the motor was pulled.

Anyways, lets hope this works. I am assuming I want to be around 65 at WOT! MY idle seems to be about right for running 30#.