* Normal Wear and Tear: This is the most common cause. The fuel pump is a constantly running motor, submerged in fuel. Continuous operation, exposure to fuel (which can cause corrosion), and vibration eventually lead to mechanical failure of the pump's motor, impeller, or seals. The lifespan of a fuel pump is generally between 100,000 and 150,000 miles, but this can vary significantly based on driving habits and fuel quality.
* Low Fuel Levels: Running the tank consistently on empty can damage the fuel pump. The pump relies on the fuel itself for cooling; running low exposes the pump to more heat and increases the chance of failure.
* Dirty Fuel: Contaminants in the fuel, such as rust, dirt, or debris, can clog the fuel filter (which is usually located near the pump) and put extra strain on the pump, leading to premature failure. This is exacerbated by using lower-quality fuel.
* Fuel Pump Relay Failure: While not a direct fuel pump failure, a faulty relay prevents the pump from receiving power, mimicking the symptoms of a bad pump. Testing the relay is a crucial step in diagnosis.
* Electrical Issues: Wiring harness damage, corrosion on electrical connectors, or a short circuit can prevent the pump from receiving power or cause it to malfunction.
* Manufacturing Defects: Though less common, faulty pumps can be produced with inherent defects that lead to early failure.
* Fuel Pressure Regulator Issues: While not directly causing the pump to fail, a faulty fuel pressure regulator can cause excessively high pressure, putting extra strain on the pump and contributing to its premature demise.
In short, it's usually a combination of age, usage, and potentially poor maintenance that contributes to fuel pump failure in a 2003 Chevy Malibu. It's a wear item, and replacement is often expected at some point in the vehicle's life.
