If you have tbi fuel injection, fuel pressure 9--13 psi. In the past on some gm vehicles, I have used pressure gage where the filter was located under the vehicle on the frame. I used the gage in place of filter to check pressure. It was easier for me to get under the vehicle then getting up under the hood, trying to squat down in the engine compartment, then taking fuel line loose from throttle body, very tight fit, no room to get pressure gage in there. So I just got underneath. If the fuel pressure is not good, check the actual voltage and ground for the fuel pump, itself. Use a digital multimeter to check actual voltage. With fuel line loose front and rear, see if you can blow through the line.