FAQ - Fuel Pressure Adjustments. afpr ?'s ALLGOHERE
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Fuel Pressure Adjustments. afpr ?'s ALL GO HERE
As with the other "ALL GO HERE" Posts...
Please this is a very common post, and in an attempt to clean up redundant posts because people are not searching first, I am asking all to post their related questions within one large post. Eventually it will contain all the information you need on this topic. (either within or linked to other posts).
So, if you have a questions relating to Adjustable Fuel Pressure Regulators. Or adjusting your fuel pressure...
Please post here. Of course, after you have searched, and after you have read the related articles..
Thank you for helping make Thirdgen better.
Please this is a very common post, and in an attempt to clean up redundant posts because people are not searching first, I am asking all to post their related questions within one large post. Eventually it will contain all the information you need on this topic. (either within or linked to other posts).
So, if you have a questions relating to Adjustable Fuel Pressure Regulators. Or adjusting your fuel pressure...
Please post here. Of course, after you have searched, and after you have read the related articles..
Thank you for helping make Thirdgen better.
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Car: '93 Full-size Truck
Engine: 350 Vortec
Transmission: 4L60E w/ shift kit
My walbro255 fuel pump is so strong it overcomes the AFPR at 17PSI. I'd like to run 13-14PSI which is recommeded by the programmer for my custom chip.
Someone suggested lowering the voltage to the fuel pump? How would i go about doing that?
Appartenty the fuel lines themselves are my restriction....
Would getting a lesser/cutting the spring in the FPR lower the PSI?
Someone suggested lowering the voltage to the fuel pump? How would i go about doing that?
Appartenty the fuel lines themselves are my restriction....
Would getting a lesser/cutting the spring in the FPR lower the PSI?
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Car: 1990 9C1 Caprice
Engine: L05 5.7L TBI 350
Transmission: 700R4 w/ 1st gear lock out
Instead of cutting the spring I recommend drilling out the weld that is in the bottom and make it adjustable, get a fuel pressure guage and fitting to dail it in exactly. I used blood sweat, and tearing, and a wood bit in my cordless drill but I got it. It was tough but its gone. cut a notch in the screw and use a flat head to adjust it.
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Car: A Camaro
Engine: Weak
Transmission: Weaker
I have the VAFPR and I can't for the life of me get the fuel pressure to go down. I've been turning the little adjustment screw CCW (lefty loosy) and it just stays at 16 psi. Should I be turning it the other way???
Tony
Tony
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Car: '93 Full-size Truck
Engine: 350 Vortec
Transmission: 4L60E w/ shift kit
I already have an AFPR, its adjusted as LOW as it can go. That is why i need other means of lowering the pressrue, such as lowering the voltage to the fuel pump...? or getting a lesser-spring?
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Car: 91 Camaro RS Convertible
Engine: 305 TBI
Transmission: 5-Speed
Axle/Gears: 3.42
What AFPR are you using? If its aftermarket with a stiffer spring just reuse the spring from your stock regulator.
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Car: '93 Full-size Truck
Engine: 350 Vortec
Transmission: 4L60E w/ shift kit
I wish it were that easy. Its turbo city's kit, it didnt come with a spring... this one is from my original FPR.
is there a certain size/demensions on the spring i can use to find another one?
is there a certain size/demensions on the spring i can use to find another one?
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Car: 90 Formula
Engine: 305 TBI
Transmission: 700r4
Originally posted by TonyC
I have the VAFPR and I can't for the life of me get the fuel pressure to go down. I've been turning the little adjustment screw CCW (lefty loosy) and it just stays at 16 psi. Should I be turning it the other way???
Tony
I have the VAFPR and I can't for the life of me get the fuel pressure to go down. I've been turning the little adjustment screw CCW (lefty loosy) and it just stays at 16 psi. Should I be turning it the other way???
Tony
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Car: '93 Full-size Truck
Engine: 350 Vortec
Transmission: 4L60E w/ shift kit
Any advice on how to lower my fuel pressure?
I'm tired of my truck always running rich, and the extra PSI is playing hell with my computer/driveablility. The custom chip is set for the stock 13PSI... never had any problems till i replaced that damn fuel pump with the Walbro 255... heh
-AFPR is adjusted as low as it can go, and i can only get as low as 17PSI... i want to have 13-14PSI.
-I'm using the same spring as the old 5.7 FPR.
Options?
-Drop the tank, use a stock pump...
-Lower voltage to the fuel pump... how?
-Find a replacement spring, one of lesser tension.. where would i find a specific spring like that?
-Tempted to just cut the existing spring... but you loose the base of it, and all the tension rests upon one coil-end.
hmm.. i'd say, cheapest one first... but no ghetto riggin'.
any advice on this one?
thanks!
I'm tired of my truck always running rich, and the extra PSI is playing hell with my computer/driveablility. The custom chip is set for the stock 13PSI... never had any problems till i replaced that damn fuel pump with the Walbro 255... heh
-AFPR is adjusted as low as it can go, and i can only get as low as 17PSI... i want to have 13-14PSI.
-I'm using the same spring as the old 5.7 FPR.
Options?
-Drop the tank, use a stock pump...
-Lower voltage to the fuel pump... how?
-Find a replacement spring, one of lesser tension.. where would i find a specific spring like that?
-Tempted to just cut the existing spring... but you loose the base of it, and all the tension rests upon one coil-end.
hmm.. i'd say, cheapest one first... but no ghetto riggin'.
any advice on this one?
thanks!
#11
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Originally posted by sniper_dsl
Any advice on how to lower my fuel pressure?
I'm tired of my truck always running rich, and the extra PSI is playing hell with my computer/driveablility. The custom chip is set for the stock 13PSI... never had any problems till i replaced that damn fuel pump with the Walbro 255... heh
-AFPR is adjusted as low as it can go, and i can only get as low as 17PSI... i want to have 13-14PSI.
-I'm using the same spring as the old 5.7 FPR.
Options?
-Drop the tank, use a stock pump...
-Lower voltage to the fuel pump... how?
-Find a replacement spring, one of lesser tension.. where would i find a specific spring like that?
-Tempted to just cut the existing spring... but you loose the base of it, and all the tension rests upon one coil-end.
hmm.. i'd say, cheapest one first... but no ghetto riggin'.
any advice on this one?
thanks!
Any advice on how to lower my fuel pressure?
I'm tired of my truck always running rich, and the extra PSI is playing hell with my computer/driveablility. The custom chip is set for the stock 13PSI... never had any problems till i replaced that damn fuel pump with the Walbro 255... heh
-AFPR is adjusted as low as it can go, and i can only get as low as 17PSI... i want to have 13-14PSI.
-I'm using the same spring as the old 5.7 FPR.
Options?
-Drop the tank, use a stock pump...
-Lower voltage to the fuel pump... how?
-Find a replacement spring, one of lesser tension.. where would i find a specific spring like that?
-Tempted to just cut the existing spring... but you loose the base of it, and all the tension rests upon one coil-end.
hmm.. i'd say, cheapest one first... but no ghetto riggin'.
any advice on this one?
thanks!
#14
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Originally posted by seanof30306
what is the 190?
what is the 190?
#15
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Originally posted by 25THRSS
It's the walbro electric pump that flows 190 lph instead of 255 lph. I'm not even sure if they make it for our cars, but I know they do for a lot of other cars. I think 255 is just too much for the low fuel pressure tbi requires.
It's the walbro electric pump that flows 190 lph instead of 255 lph. I'm not even sure if they make it for our cars, but I know they do for a lot of other cars. I think 255 is just too much for the low fuel pressure tbi requires.
#16
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Originally posted by seanof30306
but, if you're using a fuel pressure regulator, it wouldn't make any difference, would it?
but, if you're using a fuel pressure regulator, it wouldn't make any difference, would it?
#17
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Originally posted by 25THRSS
depends, some guys actually can't get the pressure down to where they want it again because the 255 is just too powerful even with the regulator bottomed out
depends, some guys actually can't get the pressure down to where they want it again because the 255 is just too powerful even with the regulator bottomed out
#18
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Originally posted by seanof30306
if that happened, you could always put a standard regulator in line before the throttle body in addition to the one after it, couldn't you?
if that happened, you could always put a standard regulator in line before the throttle body in addition to the one after it, couldn't you?
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Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
For anyone who is interested, you can make your fuel pressure adjustable and not have to disassemble it to adjust it. Just find a spare allen wrench and grind down the long end into a flathead screwdriver. When you want to adjust fuel pressure, just stick the allen wrench-driver thingy through the hole and adjust all you want. It's not great, but it works.
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Car: 90 Formula
Engine: 305 TBI
Transmission: 700r4
I've toyed with this idea, maybe someone will find it interesting enough to do. To make the pressure adjustable without pulling anything apart, why not replace the stock screw with one that extends down, beyond the end of the regulator, out that hole in the tbi, and ends in an 8mm or so hex, so you just have to reach under there with a little wrench to turn it?
Did that make sense?
Did that make sense?
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Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
It makes sense. But the only thing is that you would have to attach a washer to the bolt so it wouldn't fall out or not allow you to adjust. You could probably just weld it on now that I think about it.
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Car: 91 RS
Engine: 305
Transmission: T5
Axle/Gears: 3.73
Originally posted by MFaulkner
I've toyed with this idea, maybe someone will find it interesting enough to do. To make the pressure adjustable without pulling anything apart, why not replace the stock screw with one that extends down, beyond the end of the regulator, out that hole in the tbi, and ends in an 8mm or so hex, so you just have to reach under there with a little wrench to turn it?
Did that make sense?
I've toyed with this idea, maybe someone will find it interesting enough to do. To make the pressure adjustable without pulling anything apart, why not replace the stock screw with one that extends down, beyond the end of the regulator, out that hole in the tbi, and ends in an 8mm or so hex, so you just have to reach under there with a little wrench to turn it?
Did that make sense?
Last edited by DM91RS; 10-07-2006 at 05:53 AM.
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Car: 1992 Firebird
Engine: forged 357
Transmission: 700r4, 2200-2400 stall, vette servo
Axle/Gears: stock pegleg 2.73 drum (temp)
Originally posted by DM91RS
Yep..did it several years ago. Tap the hole for a 3/8-24 bolt and here ya go.
Yep..did it several years ago. Tap the hole for a 3/8-24 bolt and here ya go.
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Car: 1992 Firebird
Engine: forged 357
Transmission: 700r4, 2200-2400 stall, vette servo
Axle/Gears: stock pegleg 2.73 drum (temp)
drill out the weld, remove the screw, and then replace it with a bolt long enough to fit the regulator?
3/8-24tpi ?
3/8-24tpi ?
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Car: 91 RS
Engine: 305
Transmission: T5
Axle/Gears: 3.73
Originally posted by Token
drill out the weld, remove the screw, and then replace it with a bolt long enough to fit the regulator?
3/8-24tpi ?
drill out the weld, remove the screw, and then replace it with a bolt long enough to fit the regulator?
3/8-24tpi ?
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Car: 1992 Firebird
Engine: forged 357
Transmission: 700r4, 2200-2400 stall, vette servo
Axle/Gears: stock pegleg 2.73 drum (temp)
Originally posted by DM91RS
From what I remember remove the weld, the hole will be close enough in size, tap the hole 3/8-24 SAE, add the bolt.
From what I remember remove the weld, the hole will be close enough in size, tap the hole 3/8-24 SAE, add the bolt.
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Car: 91 RS
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Originally posted by Token
but I'd need a 3/8" bit to drill the weld out all the way correct?
but I'd need a 3/8" bit to drill the weld out all the way correct?
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Car: 91 Camaro RS
Engine: 305 TBI
Transmission: WC T-5
Axle/Gears: 3.73
Why is everyone allways trying to lower their fuel pressure? In general wouldn't you want more fuel pressure?
TPI Cars seem to respond very well to uping the fuel pressure. Our TBI cars don't?
TPI Cars seem to respond very well to uping the fuel pressure. Our TBI cars don't?
#32
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Car: 91 RS
Engine: 305
Transmission: T5
Axle/Gears: 3.73
Originally posted by johnjm22
Why is everyone allways trying to lower their fuel pressure? In general wouldn't you want more fuel pressure?
TPI Cars seem to respond very well to uping the fuel pressure. Our TBI cars don't?
Why is everyone allways trying to lower their fuel pressure? In general wouldn't you want more fuel pressure?
TPI Cars seem to respond very well to uping the fuel pressure. Our TBI cars don't?
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Car: 89 Firebird
Engine: L05 350 TBI
Transmission: 700r4-slippin' on it's last leg
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Car: '90 RS
Engine: 377 LSX
Transmission: Magnum T56
Originally posted by 25THRSS
because a lot of our cars come rich from the factory.
because a lot of our cars come rich from the factory.
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Car: Red 91 RS Camaro
Engine: LO3 with Comp Cam
Transmission: 700R4
Axle/Gears: 4th gen rear
Anyone want to fill me in on how to install a fuel pressure gauge so I can read whats going on? I don't really know where it even goes or how I would install it.
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Car: '90 RS
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Originally posted by iggy1991
Anyone want to fill me in on how to install a fuel pressure gauge so I can read whats going on? I don't really know where it even goes or how I would install it.
Anyone want to fill me in on how to install a fuel pressure gauge so I can read whats going on? I don't really know where it even goes or how I would install it.
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