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Old 11-21-2001, 01:37 AM   #1
LVSUBARU
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Unhappy Fuel pressure problems

Here it goes. I am installing my turbo this holiday weekend. Last weekend I did the parallel fuel mod, and installed my high flow fuel pump. I left out my stock FPR and replaced it with my cartech RRFPR. I was playing with my pressure a little, and it was running really rich at idle when cold. Then my check engine light came on, so I decided to put my stock FPR back in before the cartech, and cleared my codes. Now my pressures at idle are about 45psi! Really running rich when cold now, and the light is back. I totally took out the cartech, and my fuel pressure was still high! I did a search and found that people doing the fuel mod were having problems with their pressures being high, but I did not find any mention of a cure! I really want to figure this out before the turbo goes in! So should I scrap the stock FPR, only run the cartech, and just adjust my pressure down with the adjustments on the cartech? Is there another way? Please help! I know there has to be others that went, or are going through this problem. Thanks.
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Old 11-21-2001, 01:40 AM   #2
Eric SS
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I have the same problem. I believe the cure is getting a SVX fuel pressure regulator from what people are saying. Either that of our Cartech's just suck

Eric

Eric
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Old 11-21-2001, 01:45 AM   #3
LVSUBARU
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I read that the SVX FPR will not lower the pressure though. Imprezinator, have you done the fuel mod?
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Old 11-21-2001, 01:56 AM   #4
Eric SS
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swap and N20. gone. : (

Default

No I haven't but I don;t think that doing the mod has anything to do with the fuel pressure because the pump and regulator (or lack thereof) are pretty much what controls the pressure. EXCEPT, the easiest way to cure that (Which Ido on my racecars) is switch to a larger diameter fuel return line.

I haven;t heard anyone address this on the i-club but using a larger fuel return line will give you very good tunability of your fuel pressure. Better to be to big than small when it comes to this and I think our Subaru return line is to small.

Eric
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Old 11-21-2001, 02:48 AM   #5
skywalker
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Default Hope this helps...

Well there is a fix Andrew and I are using that seems to work quite well. Of course I will give credit where credit is do. Kaos200 told me about the SX Fuel Pressure Regulator that works very well and is actually a great addition to the fuel line modification. The only draw back of it is that it is NOT a RRFPR. It is just a simple FPR where you can set the idle Fuel Pressure and it will increase under vacuum.

Of cousre you can add a RRFPR to the list of mods and you will have everything but I was looking for something that you could set idle fuel pressure and have a RRFPR and i have found nothing that works yet. Tried a Vortech Super FMU and it did not do the job even though Vortech said it would.

As Imprezinator said I think the reason the SX works so well is because the holes in the SX FPR are much bogger and therefore less restrictive so allowing more fuel to flow through easily.

Andrew and I also found that setting the SX FPR to about 40PSI +- 2 works very well. Personally I also have an ITC, AFC and I have set the car up to retard timing and increace fuel flow. So the only time I get pinging now is in between shifts and I beleive that si because the stock injectors SUCK. So I have 440cc's goign in very soon.

As for specifically what part we used here is the info.
SX Performance
Fuel Injection Fuel Regulators
Fuel Rail Pressure Range at 0 in. Hg Vacuum 35 - 90 PSI +- 5%
So the idle fuel pressure can go pretty low
Remember this is NOT a Rising Rate FPR, but I don't think you will need one until you are boosting above 5 PSI...

Here is a link for more info:
http://www.essexind.com/sx_frame.htm
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Old 11-21-2001, 03:06 AM   #6
LVSUBARU
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How much is the SX FPR, and where can I get one?
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Old 11-21-2001, 03:18 AM   #7
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Thumbs up

i got my SX FPR for 150. Good stuff. It was funny to watch bill as he finally saw his fuel pressure go up and down when he adjusted the FPR. "Its going down?!" Hahahah. yeah the SX is nice if you cant source an SVX FPR (i couldnt find one and the places that had them wnated 100 )...plus this FPR can be taken to your next car w/o problems.


IIRC I got mine from http://force-efi.com


http://force-efi.com/sx.htm


and you want the 6AN fitting.



oh yeah i also have my vortech FMU hooked up to it as well with a 4:1 plate in it. With my programmable map I dont even hit 1500F on the EGTs.
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Old 11-21-2001, 03:19 AM   #8
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Old 11-21-2001, 03:22 AM   #9
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note: i edited my above post at the end just incase you missed it.


Hey Bill, wait till you see my EGTs. Its so nice now. Youll be like holy **** thats a huge difference. They go up nice and slow just like yours. Car pulls harder and everything.
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Old 11-21-2001, 03:26 AM   #10
Eric SS
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swap and N20. gone. : (

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Are you talking about changing "SX" to SVX"? if so, you have a little work to do still

Eric
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Old 11-21-2001, 03:33 AM   #11
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if you are talking to me Eric, my "edit" was that last piece of my post about the vortech fmu + SX FPR.
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Old 11-21-2001, 03:40 AM   #12
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Quote:
Originally posted by Imprezinator
Are you talking about changing "SX" to SVX"? if so, you have a little work to do still

Eric
They are talking about "SX performance's FPR" not a fpr from an SVX.
If anyone is interested. I may be able to get more of these. Maybe a bundle at a cheaper price? I dunno, just throwing ideas out there.
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Old 11-21-2001, 03:41 AM   #13
Eric SS
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2000 2.5RS w/ EJ22T
swap and N20. gone. : (

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OK, well I am completly screwed up and lost then. feel free to come over and kick my ass.

Eric
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Old 11-21-2001, 03:54 AM   #14
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Quote:
Originally posted by Imprezinator
OK, well I am completly screwed up and lost then. feel free to come over and kick my ass.

Eric
I wont kick your ass, just take the car
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Old 11-21-2001, 03:55 AM   #15
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On my way...
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Old 11-21-2001, 03:57 AM   #16
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It's time to kick ass and chew bubble gum....and I'm all out of gum.
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Old 11-22-2001, 02:25 AM   #17
LVSUBARU
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The website says it's adjustible from 35-90 psi. I don't think thats low enough, with my fuel mod. What do you guys think?
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Old 11-22-2001, 02:18 PM   #18
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Default Idle pressure

James,

the stock pressure is 42-43 psi at 0 vacuum (WOT on an NA motor). The SX FOR should have a vacuum port that will drop it a bit at idle. The SX should work perfectly. Some people reported idle pressures as high as 60psi with the stock FPR and Walbro pump. So if the SX will get it back down to 42, then that will do the job.
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