With the car up and running again, it was time to address one of its gray areas: fuel pressure. When working with EFI cars, a pressure test gauge is an essential tool. Loss of fuel pressure or erratic pressure levels, which are not uncommon on aging examples, will wreak havoc with engine performance, if it runs at all. This should be one of the first variables to eliminate when attempting to diagnose problems. We got a test kit from Actron that included enough adapter fittings to handle most common EFI systems. The Firebird showed a healthy 43 psi at idle with the vacuum hose off; 39-45 psi is acceptable.