Can someone clarify the best way to tune my fuel system, and what I need to have my fuel pressures at?? My current setup is: 40lb injectors, an S-AFC, and the cartech FPR. My idle fuel pressure is 40psi, and my boosted fuel pressure tops out at 100psi. I'm running 8psi of boost right now, so that gives me a 7.5:1 ratio. Is this about right? High? Low? And should that ratio change when I turn the boost up to 15psi?

From what I understand, I'm supposed to set my fuel pressures correctly, then tune the AFC fuel curve afterwards so I'm not running too rich or lean. Is that right?

Thanks in advance for all the help!

your running way to much fuel pressure. for example, i have 30lb injectors, my idle pressure is ~30psi and boosted pressure is at ~62psi @ 9lbs of boost, and im still grossly rich

Ryan I've always wondered how your FP is so low. You are using the 4.4:1 disk and 40psi static. 4.4*9=~40+40=80psi. Are you sure your FP gauge is right?

the manual gauge reads the same thing.

i have the boost screw set out to limit the fp to ~62psi.

also, i have the 2.47" disc, which is closer to a 3:1 ratio

Oh my bad. I thought you were running the 2.72"

i was originally, but it was way to rich, so i switched out discs. but after seeing my a/f readings w/ a wideband @ the dyno, i may even try the smaller disc

My idle pressure is around 30psi. i don't know how to adjust the cartech fmu to reduce my fuel pressure vs. boost, i'm at 10lbs right now and i'm sure i'm running like over 100psi on the rail.



Jon

1997 Eclipse RS

14.49@99mph 7/27/02

MODS: 8.8:1 JE Pistons / Eagle rods / Stage 1 Hahn turbocharger / Melling Oil Pump / Autometer 5" tach / 2 JL 12" W0 subwoofers / JL Audio 500/1 amp / Clarion 230w amp / short shifter mod / GReddy EVO exhaust / custom 2 1/2" downpipe / no cat con / CM Stage 1 / 30lb Mustang injectors / TurboXS MBC / 1G SMIC

Okay, I know I'm running rich, but I can fix that with the S-AFC, to a point. I just need to know what fuel pressure I need to be running at idle and at WOT, then I'll fine tune the fuel curve with the S-AFC.

I'm just confused about what fuel pressure is correct because I see some guys on here talking about 8:1 ratios, and other guys are running a 1:1 FPR.

No shit. I think we need to develop some sort of generic chart that will save/solve quite a few fuel-related questions that get asked over and over. It could be something that everybody contributes to, each with their own individual setup. From all the asking around and reading that i've done, i believe that an 8:1 ratio will be perfect for the 30lb injectors w/ cartech fmu. I still have yet to do such, because i'm trying to figure out whether to tighten the screw in or loosen it out to lower the curve. my IDLE pressure is about 35 on a cold start or 28-32 warm. ECU seems to be able to handle that perfectly. Sometimes after I start up i can feel my car bog down, but it's pulled up instantly.





Jon

1997 Eclipse RS

14.49@99mph 7/27/02

MODS: 8.6:1 JE Pistons / Eagle rods / Stage 1 Hahn turbocharger / Melling Oil Pump / Autometer 5" tach / 2 JL 12" W0 subwoofers / JL Audio 500/1 amp / Clarion 230w amp / short shifter mod / GReddy EVO exhaust / custom 2 1/2" downpipe / no cat con / CM Stage 1 / 30lb Mustang injectors / TurboXS MBC / 1G SMIC

HRC Stage1 @ 4psi -- Idle fuel pressure: 55psi, WOT fuel pressure: 90psi

Anyone else want to list their idle and boosted fuel pressures??

Thanks!