Fuel pressure question

MEDIK418 · 10-26-2002, 01:04 AM

Today I installed a second adjustable fuel pressure regulator on the 89. The Holley regulator I wasted time installing and uninstalling about 30 later was a piece of trash and I wouldn't recommend it to anyone. this one is a BBK and it is working wonderfully, not to mention it's a really neat blue one.

My question, this engine has 24# injectors and it ran really rich and sluggish while it was running the stock regulator. This new one really woke it up but I think it's still running rich at 42 psi. I know it's over-injected but, again, there are plans for a blower so he wanted to do the 24's with the MAF. (it's Hell being broke) Can some one give me an idea where it should run. It was running at 36-37 with the stock regulator but I was thinking that it should be quite a bit higher for the bigger injectors.
Anyone got a clue?

moc · 10-26-2002, 01:30 AM

do the upgrade with the fuel pump and all that ? i think it should still charge up the same under pressure . it's not the injector size ,it's the closed loop pressure thats the same . (don't quote me on this ) but the pressurization of the system has nothing to do with the injector size

MEDIK418 · 10-26-2002, 02:45 PM

You are absolutely correct. The injector size refers to the amount (in pounds) it will flow in a given time frame. My problem is I have no idea what a good starting point is for the line pressure. My understanding of the system is that the larger injectors need higher pressure to properly atomize the fuel as it is pumped into the engine. I've been told everything from 37 to 54 pounds is where I need to be. I am hoping someone here has been through this boogerboo and can shed a little light. It's running a 190 lph fuel pump and it put up 54 psi at the initial key on/engine off test.
I did try it at 50 psi for a few seconds (engine running) but it makes a real good mosquito fogger at that pressure.
Any takers?

10-26-2002, 01:04 AM	#1
MEDIK418 Registered Member Join Date: Mar 1999 Location: Amarillo, Texas, USA Posts: 780	Fuel pressure question Today I installed a second adjustable fuel pressure regulator on the 89. The Holley regulator I wasted time installing and uninstalling about 30 later was a piece of trash and I wouldn't recommend it to anyone. this one is a BBK and it is working wonderfully, not to mention it's a really neat blue one. My question, this engine has 24# injectors and it ran really rich and sluggish while it was running the stock regulator. This new one really woke it up but I think it's still running rich at 42 psi. I know it's over-injected but, again, there are plans for a blower so he wanted to do the 24's with the MAF. (it's Hell being broke) Can some one give me an idea where it should run. It was running at 36-37 with the stock regulator but I was thinking that it should be quite a bit higher for the bigger injectors. Anyone got a clue? __________________ 1986 four-eyed LX coupe, 358 Cleveland, Tremec TKO600/centerforce clutch, dish cut Probe forged pistons, comp cams hyd.roller cam, .579/.588@224/230, Edel.performer, 670 holley street avenger, CPR custom built long tubes, ported and polished 4bbl heads, manley valves, beehive springs, MSD peo-billet dist/MSD6AL, fluidamper, 5 lug conv. with 17x8 bullits there's more but it's still not finished yet. Oh, and the oldest boy is turning his 89 GT into a FFR cobra this next summer.

10-26-2002, 01:30 AM	#2
moc Registered Member Join Date: Mar 1999 Location: Ocean City , Maryland Posts: 344	did you do the upgrade with the fuel pump and all that ? i think it should still charge up the same under pressure . it's not the injector size ,it's the closed loop pressure thats the same . (don't quote me on this ) but the pressurization of the system has nothing to do with the injector size __________________ 1991 5.0 NotchBack,Black as of 05/04/09 34,300mi. 2001 LIGHTNING Black 29,872 mi. 05/04/09 (Hangar Queen) SMOKEM UP

10-26-2002, 02:45 PM	#3
MEDIK418 Registered Member Join Date: Mar 1999 Location: Amarillo, Texas, USA Posts: 780	You are absolutely correct. The injector size refers to the amount (in pounds) it will flow in a given time frame. My problem is I have no idea what a good starting point is for the line pressure. My understanding of the system is that the larger injectors need higher pressure to properly atomize the fuel as it is pumped into the engine. I've been told everything from 37 to 54 pounds is where I need to be. I am hoping someone here has been through this boogerboo and can shed a little light. It's running a 190 lph fuel pump and it put up 54 psi at the initial key on/engine off test. I did try it at 50 psi for a few seconds (engine running) but it makes a real good mosquito fogger at that pressure. Any takers? __________________ 1986 four-eyed LX coupe, 358 Cleveland, Tremec TKO600/centerforce clutch, dish cut Probe forged pistons, comp cams hyd.roller cam, .579/.588@224/230, Edel.performer, 670 holley street avenger, CPR custom built long tubes, ported and polished 4bbl heads, manley valves, beehive springs, MSD peo-billet dist/MSD6AL, fluidamper, 5 lug conv. with 17x8 bullits there's more but it's still not finished yet. Oh, and the oldest boy is turning his 89 GT into a FFR cobra this next summer.

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