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Low Fuel Pressure

My mechanic told me that the fuel pressure is about 5psi low. Could this cause jerking/bucking during acceleration?
100,000mi SS

Yes…in all likelyhood. Low fuel pressure will prevent the fuel injectors from working properly.

Usually what you describe is an ignition problem…Is your CEL on?

Never had a CEL come on.

The ODB-II system doesn’t check on the fuel system, except for monitor fuel injector feedback. Slightly low pressure will cause your issues, but the ECM is probably adjusting the pulses of the injectors to prevent a lean condition.

I’d start with a fuel filter change to see if that fixes it. After that fuel pressure regulator and pump need to be tested.

These fuel injected vehicles were designed and built to run properly at the fuel pressure they were engineered to run at. If the fuel pressure is 5psi low then obviously this needs addressed first. How can we expect an engine to run properly when it’s being starved for fuel? Of course if I remember right you have quite a bit of maintenance to perform on that car at 100k.

Today I had the catalytic converter pressure tested. He said it was fine and did not need to be replaced. He told me to change the fuel filter which I do regularly and check the Throttle Position Sensor and Mass Air Flow Sensor. I had the MAFS cleaned a few months ago. I will change the fuel filter and check the TPS.

Yup, it could easily cause jerking an d bucking during acceleration.

First of all, your ECU meters fuel by controlling the injectors’ “pulse width”, how long the injector is open. How much fuel goes through is a function of the length of time the injector is open and the fuel pressure. Lower pressure means less fuel…means poor acceleration.

Secondly, how well vaporized the fuel is depends on the pressure, and poor vaporization means poor combustion…and poor acceleration. It’s analogous to a Windex bottle. Squeeze the pump hard and a mist comes out. Squeeze it softly and it splurts out with droplets included. Fuel needs to be well vaporized to burn properly. It’s a surface area per volume thing, but I’ll spare you the boring dissertation.