Symptoms of a Failing Fuel Pump:
* Engine cranks but won't start: This is the classic symptom. The engine turns over, but it doesn't fire up because it's not receiving fuel.
* Hesitation or sputtering: The engine might run roughly, especially under acceleration, indicating inconsistent fuel delivery.
* Loss of power: Similar to sputtering, the car might feel sluggish or lack power.
* Engine cuts out while driving: This is a more serious symptom, and indicates a critical fuel supply issue.
* Weak fuel pressure: This requires a pressure gauge test (see below).
* Whining noise from the fuel tank (rare, but possible): A failing fuel pump may emit a whining sound. This is often more noticeable when the ignition is first turned on (the pump primes) or when the tank is nearly empty.
How to Diagnose:
1. Listen for the fuel pump prime: Turn the ignition key to the "on" position (don't crank the engine). You should hear a brief humming or whirring sound from the fuel tank area for a few seconds. This is the fuel pump priming the system. If you don't hear it, the pump may be faulty, or there might be a problem with the pump relay or fuse.
2. Check the fuel pump relay and fuse: Consult your owner's manual to locate the fuel pump relay and fuse. Visually inspect them for any damage. Try swapping the relay with a known good one of the same amperage from another circuit (if possible and safe). Replace any blown fuses.
3. Check fuel pressure (requires a fuel pressure gauge): This is the most definitive test. You'll need a fuel pressure gauge and the correct adapter for your fuel rail. Consult a repair manual for the correct pressure specification for your engine. Low pressure strongly indicates a fuel pump problem. This test requires some mechanical skill and safety precautions (fuel is flammable!).
4. Inspect the fuel filter: A clogged fuel filter can restrict fuel flow and mimic the symptoms of a failing fuel pump. Replace it as part of routine maintenance, but it's unlikely to be the sole cause of a complete failure.
Important Considerations:
* Safety First: Work with gasoline requires caution. Avoid sparks or open flames. Work in a well-ventilated area.
* Professional Help: If you're not comfortable performing these tests or repairs, take your car to a qualified mechanic. Diagnosing fuel system problems can be complex, and incorrectly diagnosing a fuel pump issue can lead to further damage.
* Other potential causes: Issues like a clogged fuel injector, a bad crankshaft position sensor, or other ignition components can also cause similar symptoms to a bad fuel pump. A proper diagnosis rules out these possibilities before concluding it's the fuel pump.
In short, the absence of the priming sound, low fuel pressure, and consistent difficulty starting are strong indicators of a failing fuel pump. However, a proper diagnosis requires checking the other components mentioned above to eliminate other potential causes.
