Starting Problems:
* Hard starting or long cranking: The engine cranks for a longer time than usual before starting, especially when the engine is hot or after sitting for a while. This is a classic symptom as the pump struggles to deliver enough fuel pressure.
* Intermittent starting: The car might start sometimes and not others, seemingly at random.
* No start: The engine won't crank at all, or cranks but doesn't fire – a complete lack of fuel delivery.
Performance Issues:
* Loss of power or hesitation: The engine feels sluggish, lacks power, or hesitates during acceleration. This is because the engine isn't receiving sufficient fuel.
* Stuttering or sputtering: The engine may run roughly, sputter, or stall, especially under load (e.g., accelerating uphill or passing).
* Engine stalls: The engine suddenly cuts out while driving.
* Poor fuel economy: You might notice a significant decrease in your gas mileage.
Audible Clues:
* Whining noise from the fuel tank: A buzzing, humming, or whining sound coming from the area of the fuel tank, especially when the ignition is turned on, can indicate a failing fuel pump motor. This noise might be intermittent or only present when the pump is under strain.
Less Common Signs:
* Fuel pressure gauge reading low (if equipped): If your car has a fuel pressure gauge, a low reading is a clear indication of a fuel pump problem. (Most 1991 Grand Prix's did *not* have a fuel pressure gauge).
* Fuel pump relay clicking repeatedly: A faulty relay might be an indication of a problem with the pump, though the relay itself could also be the issue.
Important Considerations:
* Check the fuel filter: A clogged fuel filter can mimic the symptoms of a bad fuel pump. Replacing the filter is a cheap and easy first step before condemning the pump.
* Other potential causes: These symptoms could also be caused by other issues like a bad fuel pressure regulator, clogged fuel injectors, a faulty ignition system, or a failing mass airflow sensor. Proper diagnosis is crucial.
If you suspect your fuel pump is failing, it's best to have a mechanic diagnose the problem accurately. Attempting to replace the fuel pump yourself can be challenging and potentially dangerous due to fuel system pressures and the need to work safely with gasoline.
