Starting and Running Issues:
* Hard starting or no start: This is a classic symptom. The engine cranks but won't fire because the fuel pump isn't delivering fuel to the engine. This is especially noticeable when the tank is low.
* Engine sputtering or hesitation: The engine may run roughly, sputter, or hesitate, particularly under acceleration or load. This indicates an inconsistent fuel supply.
* Stalling: The engine might stall unexpectedly, especially at idle or when slowing down.
* Loss of power: A weak fuel pump might not be able to supply enough fuel for higher engine demands, leading to a noticeable loss of power.
* Engine surging: The engine speed might fluctuate unpredictably.
Other Indicators:
* Whining noise from the fuel tank: You might hear a humming or whining sound coming from the fuel tank area, especially when the ignition is turned on (but the engine isn't running). This is the sound of the fuel pump working hard. The noise may be intermittent or persistent. Note that a louder-than-usual noise could also indicate failing bearings in the pump.
* Weak fuel pressure: This requires a fuel pressure gauge test, but low fuel pressure is a direct indicator of a failing pump. A mechanic would use a gauge to check this.
* Smell of fuel: While not directly indicating a *bad* fuel pump, a strong fuel smell could indicate a leak *from* a failing fuel pump, specifically a leaking seal.
Important Note: Many of these symptoms can also be caused by other issues, such as a clogged fuel filter, bad fuel injectors, a faulty ignition system, or even a restricted fuel line. Therefore, it's crucial to have a mechanic diagnose the problem properly before replacing the fuel pump, as it can be an expensive repair. A simple fuel pressure test is usually the first step in diagnosis.
