Please Help...Fuel pressure keeps moving.

Dark_5.0 · 04-05-2002, 10:37 PM

I bought an Aeromotive fuel pressure regulator and a fuel pressure gauge to help tune my speed density system. The problem is that the fuel pressure will not stay where I put it. I set it at 45psi so it will stop surging and then test drive it when I come back its at 40psi or so.

Is there some special thing you gotta do or what. The test and tune is Saturday night and I would love to have my car perfect by then cause I have a few races set up and I think if the fuel pressure drops to 40psi its gonna cost me major HP.

I have 19# injectors and the stock fuel pump.

It will stay set when the car is ideling but as soon as I go and test drive it and come back the pressure drops back down to about 40psi and stays there.

If you have any idea what I am talking about.

PLEASE HELP

Dark_5.0 · 04-05-2002, 11:39 PM

anyone

HELP

DZEE'S LX · 04-06-2002, 01:31 AM

I installed the same FPR and it seems to work well. I have mine set at 46 psi. I have a guage attached to the npt port.

I searched this topic on this sit e and got a whole bunch of theory on setting fuel pressue.

I decided to go with the guys that set pressure while the engine is off. Jimberg has posted many times stating that you should bypass the fuel pressure relay and set pressure while the pump is running with the engine off. From what I can see, it appears that setting a higher pressure is really only helping you at higher RPM's. The fuel pressure is independant from any computer controlled changes. The computer will alter injector pulses if the O2 sensors detect readings that need to be fixed. Someone else can probably go deeper into this subject.......

I did it by having a helper turning the ignition on and off while watched the highest pressure on the guage ( just before the pump shuts off after the ignition is on for about a second).

The pressure changes all over the place with the engine running depending on what the throttle setting is. Your pressure will most likely be lower with the engine running. Mine reads close to 40 at an idle.

Hope this helps, but I'm not a real expert.......

Dan

04-05-2002, 10:37 PM	#1
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	Please Help...Fuel pressure keeps moving. I bought an Aeromotive fuel pressure regulator and a fuel pressure gauge to help tune my speed density system. The problem is that the fuel pressure will not stay where I put it. I set it at 45psi so it will stop surging and then test drive it when I come back its at 40psi or so. Is there some special thing you gotta do or what. The test and tune is Saturday night and I would love to have my car perfect by then cause I have a few races set up and I think if the fuel pressure drops to 40psi its gonna cost me major HP. I have 19# injectors and the stock fuel pump. It will stay set when the car is ideling but as soon as I go and test drive it and come back the pressure drops back down to about 40psi and stays there. If you have any idea what I am talking about. PLEASE HELP __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

04-05-2002, 11:39 PM	#2
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	anyone HELP __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

04-06-2002, 01:31 AM	#3
DZEE'S LX Registered Member Join Date: Jan 2001 Location: Salt Lake City Posts: 117	I installed the same FPR and it seems to work well. I have mine set at 46 psi. I have a guage attached to the npt port. I searched this topic on this sit e and got a whole bunch of theory on setting fuel pressue. I decided to go with the guys that set pressure while the engine is off. Jimberg has posted many times stating that you should bypass the fuel pressure relay and set pressure while the pump is running with the engine off. From what I can see, it appears that setting a higher pressure is really only helping you at higher RPM's. The fuel pressure is independant from any computer controlled changes. The computer will alter injector pulses if the O2 sensors detect readings that need to be fixed. Someone else can probably go deeper into this subject....... I did it by having a helper turning the ignition on and off while watched the highest pressure on the guage ( just before the pump shuts off after the ignition is on for about a second). The pressure changes all over the place with the engine running depending on what the throttle setting is. Your pressure will most likely be lower with the engine running. Mine reads close to 40 at an idle. Hope this helps, but I'm not a real expert....... Dan __________________ Spec Service (UHP), BFG G-Force KDW's, Turbo Coupe 3.55 rear w/disks, 73mm calipers, Stg 1 Twisted Wedges, TFS Street Intake, 70mm TB, E cam, Crane 1.7's, Aeromotive FPR, BBK 1 5/8 shorties, elec fan, FMS Al Radiator, Moroso Wires, Kenne Bell Ramair, March pulleys, Race Magnums, 190 lph Walbro, FMS Al Dshaft, D/S loop, MM 4point rollbar, FMS C spngs, strut tower brace, Tokico Illuminas, Prothane bushings, MM Lwr Conrol Arms, KB welded subs, Cervini Mach 1 hood/valence/side skirts/wing/airdam.

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