61 PSIG is the normal pressure / specification for minimum pressure, but I've seen them start and run at 58 PSIG. The poppet injectors require at least that pressure to operate.
You need to test pressure both standing and when under load (higher fuel delivery) to understand the actual pressure.
Clean filters are important, ans so are reliable electrical connections. More often than not, the power connector at the top of the tank is resistive due to overheating. The ground connection near the tank is also a problem point, especially on an older vehicle. To determine if this is a problem, monitor voltage directly at the tank top connector (it's tough to get in there with probes) with the pump running.
Don't bee too surprised if you discover this:
