Fuel pressure is the key to a properly functioning EFI system. The Cross-Fire design uses a low pressure with a specification of 9-13 psi. You can use a high-pressure gauge, but we used a TBI-specific gauge for accuracy. When choosing analog instrumentation like this, the more resolution of the gauge that you can use, the more precise it usually is. The fuel pressure should be checked not only at idle, but under engine load. This will require a connection with enough length to attach it to the windshield while driving. A WOT pass in Second gear will usually reveal any flow limitations. The system should be able to maintain the idle pressure during all driving scenarios. If the pressure ramps down under load, look for a clogged fuel filter, a weak fuel pump, or low voltage supply to the fuel pump.