Welcome to the North American Subaru Impreza Owners Club Thursday October 23, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated with bolt-on Forced Induction Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 10-15-2001, 01:43 AM   #1
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Thumbs up SVX Fuel Pressure Regulator Solved Idle Pressure Problem

After installing my higher flow fuel pump (Walbro 255lph), my idle fuel pressure went up to 40-41psi, even under vacuum (stock is 30-34psi or so idling under vacuum, 40-46psi or so WOT). At the time, the engine was still NA.

After the turbo went in, along with a Vortech 4:1 Standard FMU, my idle fuel pressures were all over the place. One morning 40, the next 50, then 45, etc. This seemed to be confusing my FMU, which didn't have a stable base to begin rising from, and therefore my fuel pressures under boost were all over the place also.

As was suggested by 8Complex (and originally Al Gainey, I believe), I just recently replaced my stock Fuel Pressure Regulator (still in series with the Vortech FMU), with an FPR from an SVX.

My idle pressures under vacuum are now around 30psi or so. The car starts and idles great. Furthermore, my Vortech FMU seems much happier, with more consistent fuel pressure gradients under boost.

In all, I'm very encouraged by this. I just have one more issue to deal with on my list, and I'll be ready for some really hard testing. If everything still looks okay, I'll be taking it out to the next track day (and hopefully not towed home).

Thanks again, 8!
* Registered users of the site do not see these ads.

Last edited by the Dabbler; 10-15-2001 at 01:49 AM.
the Dabbler is offline   Reply With Quote
Old 10-15-2001, 02:00 AM   #2
Andrew
Scooby Specialist
 
Member#: 1170
Join Date: Mar 2000
Chapter/Region: BAIC
Location: San Jose, CA
Vehicle:
2005 STi
White

Default

how much did you pay, where did you get it, do they have more? ive called up some places and they wanted 100 bucks so i said GOODBYE! what about a wrx fpr.
Andrew is offline   Reply With Quote
Old 10-15-2001, 03:03 AM   #3
Ethan
NASIOC Supporter
 
Member#: 246
Join Date: Sep 1999
Default

yea after orginally reading about the SVX FPR I tried to get a used one, because I didn't want to pay through the nose. What a pain in the butt could never find a used one.
Ethan is offline   Reply With Quote
Old 10-15-2001, 03:04 AM   #4
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default

Quote:
Originally posted by Andrew
how much did you pay, where did you get it, do they have more? ive called up some places and they wanted 100 bucks so i said GOODBYE! what about a wrx fpr.
I'm glad to hear your $100 quote (for new, I assume?). I paid $50, which I thought was exorbitant, since it came off of a 10 year old wrecked car. But I needed it, and he had it. Worked out okay for me. If you're in the LA area, the place is:

World Auto Parts
5228 San Fernando Rd
Glendale, CA

Surprisingly, they actually specialize in Subaru.

I have no idea if a WRX FPR will work. The SVX FPR, FWIW, was a perfect fit.
the Dabbler is offline   Reply With Quote
Old 10-15-2001, 03:47 AM   #5
Andrew
Scooby Specialist
 
Member#: 1170
Join Date: Mar 2000
Chapter/Region: BAIC
Location: San Jose, CA
Vehicle:
2005 STi
White

Default

Quote:
I'm glad to hear your $100 quote (for new, I assume?).

Im not entirely sure if it was used or new but I only called salvaged yards who I would think only have used ones. And some did not specialize in Subarus. I called like 4 or 5 and they all gave me the BS about 75-100something.
Andrew is offline   Reply With Quote
Old 10-15-2001, 12:04 PM   #6
skywalker
Scooby Specialist
 
Member#: 1990
Join Date: Jul 2000
Location: San Diego, CA
Question

Will the SVX FPR work on a parallel line conversion? I seem to have problem with the fact that I have a parallel line setup and a High Flow Fuel Pump. My idle Fuel Pressure is around 55, WAY TO HIGH.

I am not sure if you are going to try the fuel line conversion, but before pushing to much boost I would recommend it. Don't want to blow out the 3rd piston.

I finally found the problem with the Super FMU (a leak) so my fuel pressure would be all over the place (25 - 50 at any time). Now I am trying to fix that problem. As soon as that is fixed though I am pretty sure it will work well.
skywalker is offline   Reply With Quote
Old 10-15-2001, 12:15 PM   #7
iodine23
Scooby Specialist
 
Member#: 4071
Join Date: Feb 2001
Location: Austin, TX
Vehicle:
2001 Impreza 2.5RS
Blue Ridge Pearl

Default

Why does the SVX FPR work when the stock 2.5RS one does not? Is it just a heavier duty FPR that can handle higher fuel flows?
iodine23 is offline   Reply With Quote
Old 10-15-2001, 03:56 PM   #8
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default

Quote:
Originally posted by skywalker
Will the SVX FPR work on a parallel line conversion? I seem to have problem with the fact that I have a parallel line setup and a High Flow Fuel Pump. My idle Fuel Pressure is around 55, WAY TO HIGH.
I would assume it would work, as long as you still have the OEM FPR in there somewhere. Did you take it out to run the SuperFMU in standalone mode?
the Dabbler is offline   Reply With Quote
Old 10-15-2001, 04:00 PM   #9
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default

Quote:
Originally posted by iodine23
Why does the SVX FPR work when the stock 2.5RS one does not? Is it just a heavier duty FPR that can handle higher fuel flows?
I don't have any specs to back it up, but the SVX FPR does seem to be holding where the OEM 2.5RS FPR was no longer regulating properly. The higher fuel flow requirements associated with the SVX's 230hp H-6 engine would certainly suggest a higher capacity stock FPR.
the Dabbler is offline   Reply With Quote
Old 10-15-2001, 05:57 PM   #10
skywalker
Scooby Specialist
 
Member#: 1990
Join Date: Jul 2000
Location: San Diego, CA
Default

Dabbler,

I have tried a few different things on the parallel line conversion. Actually now that I think about it, wait a tic...

A.) Stock Fuel Pump, Fuel Line Conversion (at idle)
1.) Fuel pressure was raised slightly from stock, barely though...

B.) Walbro Fuel Pump, Fuel Line Conversion (at idle)
1.) (Stock FPR only) Fuel Pressure went to ~55PSI and never changes
2.) (Stock FPR and SFMU) Fuel Pressure went to ~55PSI and would only go above that on boost, I could not lower the fuel pressure
3.) (SFMU only, barely working) Fuel Pressure could be adjusted at idle between 25-45PSI (If working 25 - 60PSI). When and if I get it working I will not need the stock OEM FPR. That is the goal because the OEM for the RS with a Walbro fuel pump and fuel line conversion will cause the stock FPR to not work correctly. From my standpoint...
skywalker is offline   Reply With Quote
Old 10-15-2001, 06:03 PM   #11
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default

Quote:
Originally posted by skywalker
Dabbler,

I have tried a few different things on the parallel line conversion. Actually now that I think about it, wait a tic...

A.) Stock Fuel Pump, Fuel Line Conversion (at idle)
1.) Fuel pressure was raised slightly from stock, barely though...

B.) Walbro Fuel Pump, Fuel Line Conversion (at idle)
1.) (Stock FPR only) Fuel Pressure went to ~55PSI and never changes
2.) (Stock FPR and SFMU) Fuel Pressure went to ~55PSI and would only go above that on boost, I could not lower the fuel pressure
3.) (SFMU only, barely working) Fuel Pressure could be adjusted at idle between 25-45PSI (If working 25 - 60PSI). When and if I get it working I will not need the stock OEM FPR. That is the goal because the OEM for the RS with a Walbro fuel pump and fuel line conversion will cause the stock FPR to not work correctly. From my standpoint...
It sounds like you're getting it to regulate fuel pressure at idle properly. That's great. Certainly cheaper than buying an SVX FPR, seeing as how you already have the SuperFMU.
It's interesting that your idle fuel pressures went up so much after putting in the Walbro pump. Mine went up to 41-43 or so, max. Of course, I didn't have the fuel rail conversion that you did, but it's surprising to me that it affected it so much.
Good luck. I still have one issue with my Standard FMU, and if I can't solve it, I may still be interested in trying out the SuperFMU.
the Dabbler is offline   Reply With Quote
Old 10-15-2001, 07:02 PM   #12
wac
Scooby Specialist
 
Member#: 689
Join Date: Dec 1999
Chapter/Region: NESIC
Location: Lebanon, NH, USA
Vehicle:
2005 Outback 2.5 XT
Champagne Gold Opal

Default

Okay, this may be unrelated, but I'm full of theories (some even turn out to be correct!). This is what I've observed on a small number of different applications:

A.) MY97 EJ22 with Supra TT pump.
1.) (Stock EJ22 FPR only) Idle at 30 psi, and will max out at 50 psi, no matter what boost (0-7 psi).
2.) (Stock FPR and Bell 20005 RRFPR) Idle at 30 psi. 50 psi at the onset of boost. At 7 psi, fuel pressure can be adjusted anywhere from 70 psi to well over 100 psi.

B.) MY98 EJ25 with Walbro pump.
1.) (Stock EJ25 FPR and Bell 20005 RRFPR) Idle at ~40 psi. 50 psi max fuel pressure, even at 7 psi. Adjusting the RRFPR didn't have any effect, and fuel pressure never goes above 50 psi.

C.) MY00 EJ25 with Supra TT pump.
1.) (Stock EJ25 FPR) Idle at ~48 psi. 50 psi max fuel pressure, even at 7 psi. Fuel pressure gauge barely moves between idle and full boost.

If the SVX FPR is too expensive, perhaps you can try an EJ22 FPR? The MY95-MY97 FPR's are interchangeable, so there's a good chance that they're also interchangeable with the SVX FPR, and therefore with the MY99+ topfeed rails as well.

-WaC
Wayne
wac is offline   Reply With Quote
Old 10-15-2001, 07:14 PM   #13
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default

That would be odd if the EJ22 FPR is stouter than the EJ25 FPR, unless perhaps they decided to keep the same FPR for both the NA and turbo versions of the EJ22? The EJ22 engine is certainly more common than the SVX's H-6, although it seems any FPR (even junked ones) isn't going to be cheap. In fact, I just called World Auto (where I got my SVX FPR), and their EJ22 FPRs are also going for $50.
the Dabbler is offline   Reply With Quote
Old 10-16-2001, 03:11 PM   #14
svxtrem
Scooby Newbie
 
Member#: 1008
Join Date: Mar 2000
Location: Grand Forks, ND
Vehicle:
2006 STI
Steel Grey Metallic

Default

The only problem you'll have is with the pressure. The SVX is calibrated for 36 psi, not the 43 psi that comes with the '99 engines. I would definitely opt for the EJ22 Turbo pressure regulator which is set for 43. Also, if you're going to replace fuel pumps, both the SVX and EJ22 fuel pumps are good for 400+ horsepower @ .55 bsfc.
svxtrem is offline   Reply With Quote
Old 10-16-2001, 03:59 PM   #15
Kevin Thomas
Street Racing Instructor
Moderator
 
Member#: 110
Join Date: Jul 1999
Location: 1997 OBS, 1996 SVX, 1988 RX
Vehicle:
1989 1989 XT6

Default Huh?

Quote:
Originally posted by svxtrem
Also, if you're going to replace fuel pumps, both the SVX and EJ22 fuel pumps are good for 400+ horsepower @ .55 bsfc.
Did you mean SVX and EJ20 or did you really mean EJ22?
Kevin Thomas is offline   Reply With Quote
Old 10-16-2001, 04:50 PM   #16
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default

Quote:
Originally posted by svxtrem
Also, if you're going to replace fuel pumps, both the SVX and EJ22 fuel pumps are good for 400+ horsepower @ .55 bsfc.
Wow! That would be immensely overdesigned, wouldn't it? Stock flow on an SVX (230hp) @ .55 BSFC is 26.3gal/hr, compared to 45.8gal/hr for 400hp at the same BSFC. Do you have a flow graph for this pump?
At any rate, the Walbro 255lph pump is also capable of the flow you describe, assuming a 43psi fuel pressure. It's the higher pressures associated with the RRFPR-type setups that really start to limit the pumps.

[EDIT: Math errors, sorry ]
Fuel flow for 230hp @ 0.55BSFC is 21.1gal/hr. 400hp @ 0.55BSFC is 36.7gal/hr. These numbers are quite a bit lower than I first posted, so the SVX pump doesn't look as much like a monster as I thought.

Last edited by the Dabbler; 10-16-2001 at 05:05 PM.
the Dabbler is offline   Reply With Quote
Old 10-17-2001, 07:44 AM   #17
svxtrem
Scooby Newbie
 
Member#: 1008
Join Date: Mar 2000
Location: Grand Forks, ND
Vehicle:
2006 STI
Steel Grey Metallic

Default

<< Did you mean SVX and EJ20 or did you really mean EJ22?<<

I meant the EJ22T (turbo model) The service manual (I have for WRX, SVX, and Legacy Turbo) list the fuel pump output in lbs/hour at rated pressure. All of them are capable of supplying 400 hp. The RS 2.5 and 'L' 2.2/1.8 are much smaller fuel pumps and have restrictive regulators.
svxtrem is offline   Reply With Quote
Old 10-17-2001, 10:32 AM   #18
yebokmj
Scooby Specialist
 
Member#: 2213
Join Date: Aug 2000
Chapter/Region: South East
Location: Raymond, NH USA
Vehicle:
1995 Impreza w/EJ257
Brilliant Red

Default My experiance

I am running the walboro 255 with the vortech 4:1 and my idle pressures are consistant and right at stock coming in at 36 lbs. I don't know why but I just thought I would mention it. I have an early MY98 maybe I am just freak? Or maybe my car just is.
Joshua
yebokmj is offline   Reply With Quote
Old 10-17-2001, 08:24 PM   #19
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default Re: My experiance

Quote:
Originally posted by yebokmj
I am running the walboro 255 with the vortech 4:1 and my idle pressures are consistant and right at stock coming in at 36 lbs. I don't know why but I just thought I would mention it. I have an early MY98 maybe I am just freak? Or maybe my car just is.
Joshua
That's interesting information. Maybe the MY98 came with a different FPR? Anyone else have this experience with an early MY98?
the Dabbler is offline   Reply With Quote
Old 10-17-2001, 08:39 PM   #20
the Dabbler
Scooby Newbie
 
Member#: 4540
Join Date: Feb 2001
Vehicle:
MY00 2.5RS Sedan
Abnormally Aspirated

Default

Quote:
Originally posted by svxtrem
The only problem you'll have is with the pressure. The SVX is calibrated for 36 psi, not the 43 psi that comes with the '99 engines.
At boost, of course, this is not an issue, assuming an RRFPR and also assuming you could figure out a proper slope to use. You just have a lower base to start rising from.

It also shouldn't be an issue running at 0 vac or below, as long as the ECU was running closed loop (i.e., 20-25% throttle or less?). The ECU should be able to compensate for the slightly low fuel pressure by adjusting the injector duty cycle (based on O2 sensor feedback).

But at WOT (i.e., open loop), while the boost is still rising (but still below 0psi), I think you're right -- this could be a problem. The ECU is relying on some fixed map inside, which assumes a 0 vac fuel pressure of 40-46 (43 nominal, if you like). Instead, it's going to get 36 psi. The RRFPR hasn't kicked in yet, because the engine is still under vacuum (or just transitioning to positive pressure). So as it's transitioning over the 0 vac/boost line, it may run lean (36psi is 8.5% less flow than 43psi, assuming equal injector duty cycles). I think I may be seeing this problem now.

I have a couple of things I want to try out to address this. I'll post if anything interesting comes of it.

Thanks.
the Dabbler is offline   Reply With Quote
Old 10-19-2001, 07:51 PM   #21
ARG
Scooby Specialist
 
Member#: 386
Join Date: Oct 1999
Chapter/Region: SCIC
Location: Upstairs in the bedroom
Vehicle:
1999 Impreza RS-S
Rally Blue & Supercharged

Thumbs down ARG

Yes, paying $100.00 dollars for an SVX FPR is quite a chunk of change. However, a used FPR out of an old XT6 is exactly the same.

I went to a local junk yard and bought an XT6 FPR for $2.00 dollars ( I had to take it off the car). I also was having idle problems with my high volume pump (RX7 Twin Turbo pump).

So if you call around, you should be able to locate an XT6 FPR used, or call PepBoys/ NAPA and get a new one for a good price.

I hope this helps, Al Gainey (ARG)
ARG is offline   Reply With Quote
Old 11-05-2001, 06:57 PM   #22
Rovah
Scooby Specialist
 
Member#: 1375
Join Date: Apr 2000
Location: Bangor, Maine
Vehicle:
2003 WRX Rally Car
Silver

Default

After reading the above posts, I'm still confused(not the first time!) if I should go with the Walbro pump or an SVX fuel pump. I'm trying to put together a turbo system that will be ok up to about 10psi or so. On the other hand, I really don't want to put in something I'm just going to have to change later!

Should the XT6 and SVX FPR work the same? I called Advance Autoparts today and got a quote of $172 for an SVX FPR! :-(

Later! John
Rovah is offline   Reply With Quote
Old 11-05-2001, 07:33 PM   #23
Kevin Thomas
Street Racing Instructor
Moderator
 
Member#: 110
Join Date: Jul 1999
Location: 1997 OBS, 1996 SVX, 1988 RX
Vehicle:
1989 1989 XT6

Default Re: ARG

Quote:
Originally posted by ARG
Yes, paying $100.00 dollars for an SVX FPR is quite a chunk of change. However, a used FPR out of an old XT6 is exactly the same.

I went to a local junk yard and bought an XT6 FPR for $2.00 dollars ( I had to take it off the car). I also was having idle problems with my high volume pump (RX7 Twin Turbo pump).

So if you call around, you should be able to locate an XT6 FPR used, or call PepBoys/ NAPA and get a new one for a good price.

I hope this helps, Al Gainey (ARG)
Thanks Al! You are two days to late. I just purchased a fuel pressure regulator for my...gues....XT6. I didn't know our cars had a fuel pressure regulator. Can this Xt6 regulator can be adjusted to increase fuel pressure right or is it regulated automatically? If so... I just wasted some $ for nothing. Guess I can throw it on the Outback Sport.

Nevermind Al! I see that the regulator is in between the fuel filter and intake manifold and the fuel return line. I wonder how I can adjust it. Is it adjustable?
Kevin Thomas is offline   Reply With Quote
Old 11-05-2001, 09:20 PM   #24
skywalker
Scooby Specialist
 
Member#: 1990
Join Date: Jul 2000
Location: San Diego, CA
Default

Stock regulators are not adjustable well nto to my knowledge they are. You have to go out and buy something adjustable for your needs.

There are many types
Cartech has one
Vortech has two

Then there are a million other small company's that carry them too.

Well I used both Vortech's with no luck but I am thinking something else on my car might be causing the problem, so I am looking into that also.
skywalker is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
WTB: SVX or upgrade fuel pressure regulator jdchmiel Private 'Wanted' Classifieds 0 02-07-2005 05:46 PM
WTB: Svx oem fuel pressure regulator GregBolby Private 'Wanted' Classifieds 1 09-22-2004 11:27 PM
SVX / 98RS / WRX Fuel pressure regulator needed. Hitokiri Private 'Wanted' Classifieds 2 06-22-2004 01:13 PM
SVX fuel pressure regulator lazybastard North West Impreza Club Forum -- NWIC 0 08-01-2003 02:27 AM
RS-T : SVX FPR swap... fixed the idle pressure problems 8Complex Normally Aspirated with bolt-on Forced Induction Powertrain 0 06-27-2001 03:12 PM


All times are GMT -4. The time now is 01:27 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.