[QB93Z]

I am trouple shooting a performance issue on my 1993 ZR-1. The car seems to idle OK but under load, there is a slight missfire or "pulsation" in the engine feel. During a full throttle run, I have gotten a DTC 55, which is fuel lean condition for more than two seconds.

The trouble shooting guide in the FSM says to investigate fuel pumps, puel pressure regulator fuel injectors and the fuel filter.

I did the fuel pump tests in the FSM. KOEO fuel pressure goes to ~ 50 psi and the drops off a little. This check is OK for both #1 and #2 pump.

I put a fuel pressure gauge where I can see it while driving. I get about 40 psi when driving.

Now my question is, what should the fuel rail pressure be when driving?

If fuel pressure is ~50 psi with the engine off, then when there is a vacuum in the plenum, does the Fuel Pressure Regulator lower the fuel pressure to maintain a constant differental pressure at the injector?

Am I over-thinking this?

Jim