How to set fuel pressure for full boost?

[ck279]

What do I do to mimic a full 6 lbs of boost on my fuel system when setting the fuel pressure. I always heard about removing the vacuum line from the JR FPR....but will that be showing the fuel system 6 lbs of boost or 0 (no boost or vacuum)?

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1993 Civic Hatch Si w/JRSC @ 6lbs

Looking for car audio?
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[217gsr]

I think I'll try my hand at answering this. Please, if I make any mistakes, correct me.

When you set the "static" fuel pressure by unplugging the JR FMU, you are setting the BASELINE fuel pressure.

The JR FMU raises fuel pressure at a 5:1 ratio when it sees boost. Therefore, if you are boosting 6 psi, and the manifold pressure is 6 psi, then you will get an additional 30 psi of fuel pressure.

If you don't have an Air/Fuel meter, I highly don't advise that you do this. If you do have an A/F meter, such as an Autometer, for instance, then you want to see about 2-3 greens all the way to redline under WOT. If at any time, you see any reds under WOT, then IMMEDIATELY come off the gas.

In essence though, you can't really set the MAX fuel pressure under full boost. You can only set the baseline with the JR FMU. Once you know your baseline, you can calculate your max fuel pressure, based on your boost reading.

Did I miss anything? I hope not.

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6 psi JRSC GSR: GSS-317, 3" intake -> 217 hp/155 ft-lbs.
New: BTC, MAP controller, and stock timing!
Soon: Endyn stepper?

[CKim]

Can't you adjust the rise rate of the JR FMU... even if it is just slightly? Or does the screw on the top of the FMU adjust static fuel pressure?

I took my A/F gauge out for now... but would it be safe to set my static fuel pressure to 58psi? Right now it's at something crazy high like 68.

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Black '00 GS-R
JRSC @ 6psi
Comptech Header / Comptech Exhaust
GC Coilovers/Tokico Illuminas
Comptech Front STB / Spoon Sports Rear STB
ITR Rear Swaybar w/ BSQ Mounting Kit
SSR GT1s / 205/45/16 Yokohama Paradas

[ck279]

So without dynoing my car, I'm looking for 2-3 greens on the air/fuel ratio gauge as a good indicator of a safe fuel setting without being too rich? What does "static" mean and why the hell is it called that?

Let me get this straight. If I am boosting at a max of 6 PSI, and the JR FPR increases fuel pressure at a rate of 5:1, by multiplying the two I will get 30 PSI. I then add that to my baseline fuel pressure to know what kind of pressure I am running at WOT. Is that correct?

Also, if the JR FPR rises fuel at a 5 to 1 ratio, then what are you doing when you play with the screw on it? Are you changing that ratio. It would seem so, as you can raise and lower the fuel pressure under boost by adjusting it.

Lastly, I do not have an adjustable FPR like the AEM or B&M. I am trying to find out the importance and procedure for setting the JR unit. Thanks!!

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1993 Civic Hatch Si w/JRSC @ 6lbs

Looking for car audio?
Give us a call! www.audio-warehouse.com

My Homepage (just started) www.geocities.com/boostedciv

[This message has been edited by ck279 (edited November 08, 2001).]

[Jumbosock]

Why are all these people driving around with a SC and no gauges to monitor engine health? How do you know what's going on in there while you are driving? Shame on you people! Just set up a fuel pressure gauge in your cockpit and put the calculators away. Besides, those calculations are only correct if you know the ACTUAL manifold pressure. Click on this link to see what I am talking about:
http://www.hostboard.com/ubb/Forum40/HTML/008670.html

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HELP, I'm drowning in rice here in Diego!

'00 Civic EX

[JRCivic]

Static fuel pressure means that there is no external force (vaccuum or boost) being applied to the diaphragm inside the FMU. This means that when you adjust the screw on top, you are essentially "moving" the internal spring to apply more or less force against the diaphragm... which in turn opens or closes the fuel outlet... ultimately raising or lowering the fuel pressure.

The JR FMU does NOT have an adjustable rise rate... you can only adjust the point in which it BEGINS to rise. For example, you stated that you wished to lower your static fuel pressure from 68 to 58 psi... and that you have 6 psi at full boost... which means that you will lower your peak fuel pressures from 98 to 88 psi.
As stated above, watch that A/F gauge like a hawk. At the first sign of a lean condition, get out of the throttle.

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'93 Civic Si H/B with B18C1, JRSC @ 8psi
Best 1320: 12.68 at 110 mph

[5 Liter Eater]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Jumbosock:
Why are all these people driving around with a SC and no gauges to monitor engine health? How do you know what's going on in there while you are driving? <HR></BLOCKQUOTE>

Word!

To see max fuel pressure I put two feet of fuel injection hose inbetween the top of the fuel filter and the B&M gauge so I can run it inbetween the cowl and hood. I can't close the hood all the way, just far enough so the latch hooks. It's just for short tuning runs. I had 2-3 greens on my A/F and thought I had it dialed in pretty good but it turned out that I was seeing over 100 PSI max fuel pressure. The A/F is really not a good tool to tune with, only to let you know when you have a problem (IE: a lean condition under boost).

Set your static pressure on the JR FMU to ~55 and you'll be fine. If you want to adjust the rise rate, get a Cartech. But get some gauges first!



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Bill Winters
'94 GSR w/ JRSC @ 9 PSI, ENDYN stepper pully, Cartech 20005, Vortech fuel modifier, RC 310's, AEM fuel rail, Hotshot 3" short ram intake, 2 1/4" test pipe and homemade CAI

[klintman]

the jr fmu's rise rate is not adjustable . the search function in the board will provide all the answers for this topic .read this thread below if you havent already .

http://www.hostboard.com/ubb/Forum40/HTML/008884.html

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99' GSR / JRSC @ 6psi
-JR MAP & BTC
-Walbro 342
-Comptech exhaust & intake/icebox
-Comptech/Koni coilovers
-Mugen 22mm rear sway bar

[This message has been edited by klintman (edited November 09, 2001).]

[CKim]

Okay... I think I get it now.. kind of.

So I use the screw on top of the JR FMU to adjust my static FP, right?

What do I use my AEM FPR then? To adjust my idle FP? What do I want THAT set to?

Thanks.

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Black '00 GS-R
JRSC @ 6psi
Comptech Header / Comptech Exhaust
GC Coilovers/Tokico Illuminas
Comptech Front STB / Spoon Sports Rear STB
ITR Rear Swaybar w/ BSQ Mounting Kit
SSR GT1s / 205/45/16 Yokohama Paradas

[grand600]

I have also used a different method don't know if it right or wrong but it seems to work. I have a vacuum gun that also switches to pressure or boost as we call it. I pull the line of the jr fmu and start the car. Then I apply 6psi of pressure to the FMU this shows me the exact full boost fuel pressure. Seems like a good theory to me.

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JRSC 6psi(soon to be 8)RC 270's, cartech 2025i water inj, jr map mod, vpac, JR BTC, dcsports 4-1, apex-i N1 catback 2.5", stock cat(my bad), J&S safeguard, (JR 8psi upgrade), fuel pump, aluminum fly(6.5)lb, center force dual friction clutch. A/F gauge, FP gauge, boostgauge. and big old crappy Konig rated "R" 17's this thing is sure to be slow