93 LT1 383 Fuel Problem

[Gio93z]

OK...Real quick....Holley 255lph fuel pump.....accell 30lb injectors....aeromotive fuel pressure regulator......

Vehicle is a 93 LT1 383 bored/stroked - ported polished LT1 heads.....ported intake manifold....58 mm TB.....SS hood w/ functional ram air

Before the heads, intake and TB, the car ran way lean on the dyno while doing some pulls - I assume that after I did the other top end mods, it is running just as lean if not worse

Finally had the car dropped off to be tuned. Vehicle dropped off at Bruce's Speed Shop. They reposition my TPS and messed with my IAC. The car used to stall sometimes at start up where-as now that problem is solved. He could not complete the tune because he said at higher RPM's, while driving the car on the road, the fuel pressure drops a bit rather than increases. He did not even bother to adjust my fuel pressure via the ADJUSTABLE regulator. He said I should fix that problem and then drop the car off again.

Personally, I thought the tune could remedy that problem. That's why I wanted it tuned in the first place.

Am I missing something with my fuel set up? The stock max idleing fuel pressure is 44psi. I was actually at around 42 - 43psi when he was 'tuning' my car. I just today, bumped my fuel pressure up to an idle psi of 50psi but only drove the car for about 10 minutes just trying to go home. I noticed my air fuel gauge instantly responded to this: it was finally going into the GREEN/RICH. I'm going to drive the car tomorrow a bit on the highway and really see of my problem was as simple as giving her some fuel pressure.


ANYONE have advice??

Gio

[JSPERFORMANCE]

The tune is not going to affect fuel pressure, that is governed strictly by the regulator, if there is drop off at high rpm the you have a fuel flow froblem ie. clogged filter, pinched line, or bad fuel pump..

[Pampered-Z]

Also, and probably not what you want to hear, but the first thing I would do is dump the Areomotive AFPR. They have had issues with the LT1 fuel rail mounted ones. Not upping fuel and also pushing FP too high. Put the stock FPR back on and see what happens.

[Gio93z]

Well, what's you're ideal set-up if you went aftermarket in regards to the fuel pump, AFPR, and injectors.

The set up I have are Accel 30lb injectors, Aeromotive AFPR, and Granatelli Electronic Fuel Pump.

I relocated my fuel pressure guage temporarily onto my wiper cowl so I could check it out while I was driving. At idle the fuel pressure is currently at 50psi. If I tap the gas, it goes upto about 52-54 psi, then down to about 47-48 psi and then settles at 50 again. While driving, if I give it about 3/4 gas, teh fuel pressure blips upto around 55psi then stays around 42 - 47 psi while I'm still into the throttle. I'm still feeling as though even if it drop to 42psi while into the throttle, I'm not in a lean condition, but should it drop that low while I'm into it?

I personally feel as though my injectors are fine so basically what pump and regulator might be ideal? FYI, I don't have my stock FPR anymore, nor would I put a non adjustable one on.

Thanks.

[sinistr]

i would look into the racetronx fuel pump systems .. loseing 10 psi under 3/4 throttle is a little outlandish ... could also be something electrical ..dirty pump screen ...dunno.

after i put a new pump in my car 255 granatelli one of the fuel lines coming from the pump had a little slice in it...just throwing ideas out there

[Pampered-Z]

30# should handle 500HP no problem without maxing out duty cycles. Can you check the voltage to the pump. I run the racetronix with the harness that draws power right from the alt. Maybe you could look into a boost a pump to add voltage that will increase the pump's output?

AFPR really don't have that much effect on our engines. Turning up the pressure will only add fuel to the engine until the ECM adjust and shortens the injector pulse to compinsate for the extra fuel.

but those that use AFPR for N/A cars seem to have no problems with the Holley units.