Ok I had the original disc that comes with the unit in but not enough FP. So I put in the next size down and put in the bigger spring and still not enough..
I tried putting the original one in and the second to the smallest and still 20 idles FP.

So I have tried every disc ecept for the smallest one??


How do these things works and what disc should I sue?????????????????
I am trying to get like 45-49 idle pres.

Help
thanks
Mark

Okay not sure if this applies....but here is how you find the proper disk you need for boost.

From Hahn's insturctions (Section 5: road test and adjustment)
"For standard non intercooled....blah blah....
@ 6 lbs ===> 80-90psi of fuel
@ 9 lbs ===> 105-110psi of fuel"

Here is how you solve for slope (Linear relationship between boost and fuel pressure)

Assuming you want to run slightly rich to prevent leaning , we'll use 90psi and 110psi as our Y value.

remember Y=MX+B

And M (slope)= rise/run

Your two data points are (6 , 90) and (9 , 110)

slope= (110-90)/(9-6) ==> 20/3 ======> 6.666666 roughly 7:1 disk

hope this helps out. MAkesure someone else check my math but I'm fairly sure this is the relationship and the disk you need to run safe boost.


good luck...
kaiser

huh???

I don't know what all that means but thanks..

All i know is that I have 4 diff disc and none of them are giving me enough FP. Something isn't right. What should I do.

What disc do I use the one that came with the unit with no ring, OR the next one smaller that does have a ring, or one of the two after that???

Then should I continue to use the taller spring or the shorter spring??

Thanks

Have you tried adjusting the base pressure set screw? The discs only adjust for boosted fuel pressure, not idle.

The DISKS ONLY help with the BOOSTED FUEL PRESSURE.

STATIC or IDLE fuel pressure:

To adjust the idle fuel pressure, put in the shorter spring. Although it's shorter, it actually is provides more unspring length than the one that was already in the SFMU when you bought it. Next, adjust the silver allen bolt that protrudes from the top of the S-FMU and screw it in or out as needed to give you the needed idle fuel pressure. (47-55psi)

BOOSTED FUEL PRESSURE:

The LARGEST washer/disk should work to give you the fuel pressure you need. The largest disk requires no ring and should almost provide too much fuel pressure. It does for my car and almost hit 120psi at 8 psi. I need to lean it out a tad with the bleed screw.

The largest disk was the disk that should have already been in the SFMU at the time you received it. I believe it's the 3.49" or so disk. I know it's 3-something.

Actually when I got the sfmu it had the smaller one (spring) in there and Corbin told me to put in the longer one.

I tried adjusting the shorter one and I screwed it in as far as I could till I couldn't get the locking nut back on.. and it still wasn;t enough FP.

So I then put in the longer spring and it was about the same way a little better but still not high enough and could barely get the locking nut back on.

So I guess I am going to put the original disc back in or should I put in the next one.

Darkone you are talking about the static press screw right??

Put the original, largest disk in.

I have the Vortech S-FMU unit for me as well. The largest spring isn't necessarily the tallest as it stands up. It's a little thicker.

You should be very careful when srewing that screw all the way in. The instructions explicitly warn that you could damage the internal diaphram if you screw it too far in. That's why the instructions note to change out springs if you need a higher static fuel pressure.

Static fuel pressure = idle fuel pressure = middle allen screw... NOT THE DISK.

Ok cool
Should I just put in the smallest spring??

If I stand the two springs up next to each other, one does stand taller than the other, which one should I throw in there the one that looks taller or the shorter looking one...

Thanks
Mark

"To adjust the idle fuel pressure, put in the shorter spring."

The shorter one.

Ok well I put in the bigger disc, then i put in the smaller spring in and cranked the static screw about 95% and still only got about 25-30.

So I put in the larger spring and cranked it down and still got about the same a little higher press but not much I am still at like 35.

Corbin says I need the optional spring so He is going to find that for me. Cause I have tried everything and everycombo with what I have.

I have plenty of boost fuel press, but idle still sucks.

Is it ok to drive untile I get the other spring, It doesn't matter as long as the boosted fuel press is high, Correct????

I'll work on getting that optional spring for you. I guarantee that will solve your problems. With the optional spring and the 2.72" disk (5.4:1) you will get the right fuel pressures for 6 psi boost. With this combination, you can get 41 psi at idle vacuum, 56 psi at 0 boost, and 84 psi at 6 boost. That is perfect for stock injectors and the HRC turbo (need 80-90).

Jason...my instructions say to put in the spring with the longer free length for more idle fuel pressure. My S-FMU came with the short spring installed. Neither of the included springs gave me enough idle pressure (same with Mark). These two springs are essentially the same thickness and finish. I bought an optional third spring that was short, thicker winding, and dark finish. This was the only way for me to get proper idle pressure. Vortech is denying the existance of this spring, but I'm trying to get another one for Mark. Maybe your S-FMU came with this spring standard? Here are the two springs that came with my S-FMU:


Corbin

'95 ESI-T
HRC+FMIC+ETC...

So now that I have all kinds of FP under boost and running really rick, I burned up my O2 again today and have the CEL on along with code 21 I have code 14 and that started after I installed the VC2 is this normal.

anyway can I run more boost since I am reall realy rich????
like 6 or 7 ???
everything is stock on stage I

>So now that I have all kinds of FP under boost and running
>really rick, I burned up my O2 again

Don't trash the O2 sensor yet. Give it several miles of light cruising and it might start working again. If you run really rich, your O2 can get screwed up temporarily. They can often "self-clean" after a few miles of light duty.

>anyway can I run more boost since I am reall realy rich????
>like 6 or 7 ???
>everything is stock on stage I

You can run 6 with a stage I. But I wouldn't turn it up until you have your fuel system right. The fuel pressure will rise with the boost pressure. If you had too much fuel at 4-5 psi, you have even more extra at 6 psi. I'd suggest driving lightly until you get your fuel system right.

Corbin

'95 ESI-T
HRC+FMIC+ETC...

Huh really?....well, my FMU did come with two springs and had the taller one installed already.

As you might remember, I also had the same idle problems (the idle was too low) being that I would turn the idle pressure screw all the way in until it appeared to bottom out without being able to bring the idle to the level I needed. Then I swapped to the shorter spring, assuming that was the one with more "unpsrung length" also from the reading of the instructions, and voila...I was easily able to adjust the idle to the necessary 50 psi.

I admit, the "unsprung length" language was a bit confusing to me given that the taller spring was already installed. I deduced from the statement and the already installed taller spring to mean that the shorter spring had more unsprung length. Oh well...all in all the shorter spring turned out to be the spring that did the trick for me.

Jason...do your two springs look like the ones in my picture? I really wonder if you got the "third optional spring" with your S-FMU. Vortech said something about that spring being incorporated into the new S-FMU kits. With both of the springs pictured, I (like Mark) could not get enough pressure. I really want to know whats going on here.


Corbin

'95 ESI-T
HRC+FMIC+ETC...

Well, I'm trying to recall. There are two things I distinctly noted about the "other" spring I had. First, in comparison to the one that was already in the SFMU, it was easily shorter. And second, the second spring was decidedly more rusted looking in color as compared to the two springs in your picture. The one within the SFMU was shiney and metallic in color much like the ones in your picture. However, the optional second spring was almost a rusted brown-ish color.

As far as making any guesses as to how tall my taller (or shorter) shiney spring is compared with either of your springs are, we'd have to measure both. I can masure my taller spring if you like. :-)

I really think your S-FMU came with the optional hard spring (7X100-050). That one is short (like the small one in my pic) and a very dark brownish color. That has got to be the problem here. Hopefully I can straighten this out with Vortech on monday.


Corbin

'95 ESI-T
HRC+FMIC+ETC...