adjusting/setting fuel pressure
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From: Beautiful BC
Car: '88 IROC-Z / '91 Z28 / '91 GTA
Engine: LT4 Hot Cam 305 / L98 355 / MR 383
Transmission: 5-spd / 700R4 / 700R4
Axle/Gears: 3:45 / 3:23 / 3:23
adjusting/setting fuel pressure
ok guys.. here is my dilema. I currently do not have a fuel pressure gauge nor do I know anyone that would lend me one. I've replaced my fuel rail and replaced the adjustable frp with a tpis unit. As per instructions, I tightened the bolt until it contacted the washer and then gave it one full turn. Car runs, but it is pig rich.
My question is does tightening the bolt more increase or decrease the fuel pressure?
My question is does tightening the bolt more increase or decrease the fuel pressure?
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Joined: Feb 2002
Posts: 3,462
Likes: 4
From: N. Illinois
Car: 92 GTA/ 00 TA
Engine: 383/350
Transmission: 700R4/T-56
Re: adjusting/setting fuel pressure
Correct. You could probably "rent" a fuel pressure gauge from one of your local parts stores.
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From: Franklin, TN
Car: 92 B4C 1LE/2010 GT/2003 P71/2002 Z2
Engine: 5.7/4.6/4.6/5/7
Transmission: A4/A5/A4/A4
Axle/Gears: 3:23/3:73/3:23/3:73
Re: adjusting/setting fuel pressure
Yeah, Checkers/Advance sells them for $60, very useful addition to any modern mechanic's tool box. But they also rent for like $6 a day,you pay in full, then get a refund when you bring it back. On my AFPR I had to back it all the way off to get it down to 44 range.
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From: Elk Grove Village
Car: Firechicken
Engine: 350 + 30 over, 400 crank
Transmission: autotragic, stalled
Axle/Gears: not a one tire fire, thank god!
Re: adjusting/setting fuel pressure
I have the tpis unit. Not bad. I got my fuel pressure gauge from DangerZone and it was like $40 for the Actron unit. My AFPR is backed off quite a bit and I'm still at 51 psi. My car likes 55 psi but don't do that if you're stock. No point to it.
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Joined: Dec 2005
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From: East Brunswick
Car: 1987 Pontiac Trans Am
Engine: 305 TPI
Transmission: Auto
Re: adjusting/setting fuel pressure
ok so if i have a 305 tpi with a flowmaster exhaust 3 inch from cat. how much fuel pressure should i have
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From: Beautiful BC
Car: '88 IROC-Z / '91 Z28 / '91 GTA
Engine: LT4 Hot Cam 305 / L98 355 / MR 383
Transmission: 5-spd / 700R4 / 700R4
Axle/Gears: 3:45 / 3:23 / 3:23
Re: adjusting/setting fuel pressure
ok I bought a gauge and set my car to 46psi.., seems to respond well at this setting so far. I also found this which helped me do this properly;
The correct method for setting fuel pressure is to:
1) connect the fuel gauge securely with no fuel leak
2) start engine, let engine idle down to proper idle RPM
3) disconnect & plug vacuum line from plenum to AFPR
4) read your fuel pressure.
Stock fuel pressure should be at 43 to 44 psi.
With mods, you might want more than stock fuel pressure. Also, realize that the fuel pressure is set for the correct AFR at WOT, not for idle or for cruizin around.
1) connect the fuel gauge securely with no fuel leak
2) start engine, let engine idle down to proper idle RPM
3) disconnect & plug vacuum line from plenum to AFPR
4) read your fuel pressure.
Stock fuel pressure should be at 43 to 44 psi.
With mods, you might want more than stock fuel pressure. Also, realize that the fuel pressure is set for the correct AFR at WOT, not for idle or for cruizin around.
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Joined: Jul 2007
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From: Elk Grove Village
Car: Firechicken
Engine: 350 + 30 over, 400 crank
Transmission: autotragic, stalled
Axle/Gears: not a one tire fire, thank god!
Re: adjusting/setting fuel pressure
For enyce31082, all I can say is that with a catback, changing fuel pressure won't do much. Maybe help throttle response a bit but not much more. It's kinda like an airfoil, it doesn't do much to a bone stock or mild modded car, but once you keep adding mods, the airfoil and AFPR does help.
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Joined: Jan 2002
Posts: 195
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From: Franklin, TN
Car: 92 B4C 1LE/2010 GT/2003 P71/2002 Z2
Engine: 5.7/4.6/4.6/5/7
Transmission: A4/A5/A4/A4
Axle/Gears: 3:23/3:73/3:23/3:73
Re: adjusting/setting fuel pressure
Hmm, differing opinions on this one...some sources have claimed up to a 15 RWHP increase by optimizing the fuel pressure on an otherwise stock engine. I certainly noticed a difference in mine.
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From: Charles County, Maryland
Car: 2000 BMW M5
Re: adjusting/setting fuel pressure
You will only notice a difference if your tune is sub par for your combo. If you burn chips and datalog, changing the fuel pressure is not required because you can get the tune set properly.
Joined: Feb 2001
Posts: 8,494
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From: Sophia, NC
Car: 2016 Camaro SS + 1986 Z28
Re: adjusting/setting fuel pressure
There's only one "right". If you saw gains, then it WAS wrong, and you made it better. ...beyond that, it's for fine tuning, not really for "performance" so to speak.
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