Dropping Fuel Pressure from 48 to 45. Make a Difference at Idle?
Thread Starter
Joined: Jul 2010
Posts: 833
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From: The Jersey Shore
Car: 1991 Firebird Convertible
Engine: 5.7 L98
Transmission: 700R4
Axle/Gears: 3.45 9 Bolt Posi
Dropping Fuel Pressure from 48 to 45. Make a Difference at Idle?
My car runs really rich during cold open loop idle. Do you think if i scale back the fuel pressure from 48 at idle with vacuum line disconnected to 45 it will make a difference?
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iTrader: (1)
Joined: Feb 2010
Posts: 467
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Car: 85 Trans Am
Engine: 98 Vortec 350 LT1 Cam w/ TPI
Transmission: T56
Axle/Gears: 9 bolt 3:27
Re: Dropping Fuel Pressure from 48 to 45. Make a Difference at Idle?
Someone may correct me but I'm pretty sure you should be at 43PSI with vacuum disconnected. And yes just a few lbs will make a difference at idle.
Thread Starter
Joined: Jul 2010
Posts: 833
Likes: 17
From: The Jersey Shore
Car: 1991 Firebird Convertible
Engine: 5.7 L98
Transmission: 700R4
Axle/Gears: 3.45 9 Bolt Posi
Re: Dropping Fuel Pressure from 48 to 45. Make a Difference at Idle?
hmm... the spec on all data reads the following, but it dont say anything for engine idling vacuum line off
FUEL PRESSURE:
Ignition ON Engine OFF ....................................... 40.5 to 47.0 psi
With Regulator Vacuum Applied [1] 3.0 - 10.0 psi Less than Ignition ON Engine OFF
REMARKS:
[1] May be checked with either of the following methods.
^ With Pressure Regulator Vacuum Line Attached at normal idle speed.
^ Ignition ON Engine OFF with 10 Inches Of Vacuum Applied To The Pressure Regulator.
FUEL PRESSURE:
Ignition ON Engine OFF ....................................... 40.5 to 47.0 psi
With Regulator Vacuum Applied [1] 3.0 - 10.0 psi Less than Ignition ON Engine OFF
REMARKS:
[1] May be checked with either of the following methods.
^ With Pressure Regulator Vacuum Line Attached at normal idle speed.
^ Ignition ON Engine OFF with 10 Inches Of Vacuum Applied To The Pressure Regulator.
Thread Starter
Joined: Jul 2010
Posts: 833
Likes: 17
From: The Jersey Shore
Car: 1991 Firebird Convertible
Engine: 5.7 L98
Transmission: 700R4
Axle/Gears: 3.45 9 Bolt Posi
Re: Dropping Fuel Pressure from 48 to 45. Make a Difference at Idle?
well i turn my crane AFPR counter clock wise and no change stays at 48 at idle vacuum line un hooked....
turn it clock wise pressure goes up...
any ideas?
turn it clock wise pressure goes up...
any ideas?
Joined: Apr 2005
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: Dropping Fuel Pressure from 48 to 45. Make a Difference at Idle?
Member
iTrader: (1)
Joined: Feb 2010
Posts: 467
Likes: 6
Car: 85 Trans Am
Engine: 98 Vortec 350 LT1 Cam w/ TPI
Transmission: T56
Axle/Gears: 9 bolt 3:27
Re: Dropping Fuel Pressure from 48 to 45. Make a Difference at Idle?
If your regulator is the stock style with a screw in the top then you may not be able to go any lower.
Either that or there may be a blockage in your return line somewhere.
Either that or there may be a blockage in your return line somewhere.
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