DougSilver

I have a 95 LT-1 with slight mods. My stock fuel pressure was 46psi with the car running and vacuum disconnected. I have played around slightly increasing and slightly decreasing from this setting. Before the "cold spell" here in LA (50-60 degrees) I had the pressure set at about 48psi. I noticed the car had a sort of "heavy" feel--really had to put my foot into it to feel performance. I figured with the cooler weather, the car was running rich? I started tweaking the pressure down and am now at about 43 psi. The car seems much more "responsive" (i.e., smaller movement of the gas pedal is needed). By reducing the pressure I assume I have "leaned" out mix? I realize that the PCM is probably increasing the pulse width to compensate for the reduced pressure.

Anyone else have experience trying different pressures or do most just crack it above stock by a few psi?

C4-Wolf

I have had similar experiences changing mine around. Low rpm response was a bit better when my pressure was at 42 psi, but high rpm suffered some. It is now at 47 psi and pulls much harder from 4500-6300 rpm. I have heard that in general, L98's run better at about 47psi and Lt1's run better at generally lower settings. (With few modifications that is.)
I am going to dyno mine as soon as I get the motor back together. I figure I will try different fuel pressure settings each run and see how it turns out. I'll let you know what I find.
Also, I can tell you I failed an emmisions test while running at 50 psi, but passed easily when running at 42psi.
Jeff

RayJay

This question of fuel pressure has been bugging me since I added the adjustable fuel regulator to my ' 96 LT-1 coupe. I bought mine from TPIS and their literature (TPIS 2000 Catalog, pg 2) and based on a conversation with someone from TPIS, they like 39 PSI for the LT-1s. I don't have a gauge so I don't know what my regulator is currently set for so I'm interested too.


Regards,
-RayJay-

DougSilver

Mine is a TPIS also. I called someone there shortly after getting the regulator and they also recommended 39psi. When I initially tried that, the car ran crummy so I set it back up to stock+. In retrospect, I think the problem was that I did not allow enough time for the PCM to compensate for the lower pressure. TPIS also recommends making the adjustments in small increments (about .5 psi at a time). By the way, I bought the pressure gage from Pep Boys and I would highly recommend it. It has a second small hose and pressure release button that allows you to bleed off the fuel after reading the pressure rather than having fuel spray out of the main hose when disconnecting.