In preperation for my new Bosch III injectors I've planned on replacing the fuel filter and check pressure. I checked yesterday and found at cold idle the pressure was 37PSI. It would jump up to ~45PSI if I blipped the throttle but would go back down to 37 in less than a second. From the appearance I suspect the regulator is original on my '95 so I'm not opposed to replacing it. Should I wait to measure again after replacing the filter or is it best to get a new one? If so what brand?

 

Thirty-seven PSI seems a bit low for a '95 LT1. My '92 pulls 40-41 at cold idle. Definitely go ahead and get the fuel filter changed and measure again. The brand of fuel filter isn't all that critical. OEM equivalent available at any auto parts store should be fine. If after you install the new filter and pressure is still under 40 lbs. at cold idle, I would start looking toward your fuel pump as a potential for low the low pressure.

Do you have access to an OBDII scan tool and to a factory service manual for your year? If so, check your fuel trims both before and after the injector swap. I had installed a set of the yellow 22# Bosch IIIs in my car and my fuel trims went way lean. Jon Banner from FIC swapped them for me with a set of black 23# Bosch IIIs which brought my fuel trim readings back to near normal levels, but still a tad lean. At the time, Jon was thinking that the 23# units would work better in an LT1 and he was right. Keep in mind, the Bosch III injector is about the closest thing to the original Multec injectors available, but they do have different operating parameters. If you're running low fuel pressure with the stock injectors and switch to the 22# Bosch IIIs which sometimes have a tendency to run lean for an LT1, you're going to be severly lean with the new injectors.