Fuel Pressure Problem

[Holden]

Lundgren: On your website, you say:

"Fuel pressure should be 50psi at idle with the vacuum line connected, 60psi at idle with the vacuum line disconnected. At WOT 6psi of boost, the pressure floats around 85psi. From 0 to 4.5 psi of boost (that's zero vacuum zero boost) the pressure rises from 60 to 85psi at about a 5:1 ratio. "

Do you still stand by this?

My FP at idle with the vacuum line connected is 57psi, it max's out my gauge at 99+psi at full boost (I'm seeing 9psi boost - another problem), and my A/F is in the richest 2 stoich/yellow LEDs at WOT/Full boost. Another thread is currently saying this is too lean.

Maybe I could cure some of this by lowering the baseline FP to 50psi as you recomend. Lower FP's could get me a richer mix since I have the regular pressure pump.

What do you think?

BTW, my FP goes up to 68psi at 0 boost. What could that mean?!?!

(And a hex on all of you who were calling the high pressure pump "unneccesary" last fall and got me to buy the regular one! JK)

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Greg Holden
96 GSR, JSRC, Walbro regular pressure pump, AEM cai,
RSR headers, Greddy PE, Brembo Cross-Drill rotors,
DC Sports Rear Strut Tower Brace (junk!), Yoko AVSi

Greg Holden's JRSC Install Site

[Turismo]

If your seeing 68psi with the vac line disconected (guage at the fuel filter or in line before the rail in your case) I'd say your JR FPR is set too high. Mine was set pretty high until I installed the B&M and could get a true reading. Try backing it down until you have 55-60 with 0 vac and see what happens. I would think you will lower your top pressure a respectable amount. I havent had the lean condition you speak of but I'm only at 6psi (not sure in yours) but it seems like it could be the pump pushing it's limits from the flow charts from Walbro.

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'96 JRSC GSR Sedan (Black Currant Pearl)
AEM CAI / PMS
J&S Safeguard / Walbro HO Pump
DC Strut Braces Skunkworks Rear Swaybar
H&R OE Sports Billstein HD's
(8psi pulley on deck)

[lundgren]

Well for most 6psi kits, yes, but I've since then think that more, even 60psi with the vacuum line disconnected from the FRP may be good.

[Holden]

I'm at 6psi.

So the fuel pressure I see at 0 boost is approximately what I will see when the vacuum line is removed.

So I am running 8-13psi too high baseline.

I will commence tinkering!

[lundgren]

Yeah, but 60 isn't bad, 70 is high.

[JRCivic]

Greg,

60 psi is where you should be with a typical 6psi kit (+/- 2psi).

Now, the amount of boost that you claim to have concerns me... 9psi isn't normal for a "Stock" kit. However, given this is correct, your static fuel pressure should be 62-64psi.

Lastly, stop messin' around and BUY a High Pressure 255lph pump, or buy some larger injectors so that you can LOWER your fuel pressure.

At WOT, your A/F gauge should be rich... really rich !!! Anything less is unacceptable.


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

[Turismo]

Jim,

How rich is "really rich" and whould it hurt to run one led into the rich with a slight shift to the first stoich led once in a while?


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'96 JRSC GSR Sedan (Black Currant Pearl)
AEM CAI / PMS
J&S Safeguard / Walbro HO Pump
DC Strut Braces Skunkworks Rear Swaybar
H&R OE Sports Billstein HD's
(8psi pulley on deck)

[Holden]

Thanks Jim.

I'm going to try lowering the baseline pressure and see if my a/f gets richer. If it doesn't, you'll be getting an order from me this week.

Which would you recomend? Pump or injectors? I don't plan on going past the 6psi kit.

Also, I worry that my cat is clogged and is causing the high boost I'm seeing. Have you seen cats clog in 46K miles? Any advice on replacing it? I was thinking Random Tech.

Thanks again,



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Greg Holden
96 GSR, JSRC, Walbro regular pressure pump, AEM cai,
RSR headers, Greddy PE, Brembo Cross-Drill rotors,
DC Sports Rear Strut Tower Brace (junk!), Yoko AVSi

Greg Holden's JRSC Install Site

[rjaffey]

Your results may vary, but I installed a high pressure pump a couple of weeks ago and found that I got the most power when I lowered the reference pressure (w/o vaccuum) to around 50psi. The pressure still hits around 85psi at 6.5psi of boost. When I had the reference pressure at tad over 60, the car was slower in successive 30 to 60 pulls in second gear. The downside is the car hesitates a tad when boost first kicks in. I'm going to tune it out with a Cartech regulator when it shows up this week. I ordered mine before Lundgren ordered his, but he got his first. :P Go figure.

Why did I replace my pump? The one I had started having lots of trouble maintaining any kind of volume at 80psi of pressure. The car got slower.

BTW, the timing was done with an "ET timer" which reads pulses from magnets attached to the inner CV joint. The thing's quite consistant if there's no wheelspin and 30 to 60 requires no shifting so that's out of the equation as well.

Holden,

If your car's really boosting to 9psi due to higher airflow (maybe you've got a smaller crank pulley), you probably need more fuel than the pump can supply at the pressure you need with the stock injectors.

[1fstGSR]

Talked to Jim for you Holden:

If you are planning to go more boost, etc. then it would be best to do both fuel pump and injectors with the adjustable riser.

If you are going to stay with what you have for a while then just do the pump because the stock walbro really does run out of flow at 80-85 psi and over time will cause problems.

As far as the A/F, you really need to have the 2nd and 3rd lights of the rich lit up when running in the first 3 gears, 4th and 5th should not run lower than 1st and 2nd lights (both on at same time) ever. If you do you are running lean and your exhaust temps are probably going through the roof
(This is from experience bro )
give jim a call if you have a second if you still have any questions.
later,
Will



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13.24 on a smokin' motor can't be bad!?!