* Age and Wear: The most common cause. Rubber components within the pump, like seals and diaphragms, degrade over time due to exposure to fuel and heat. This leads to leaks, reduced pressure, and ultimately failure. 35+ year old parts are particularly susceptible.
* Corrosion: Rust and corrosion can damage the pump's internal components, especially if the fuel tank is rusty or contains water.
* Low Fuel Levels: Running the tank very low frequently can cause the pump to overheat as it's not adequately cooled by the surrounding fuel.
* Dirty Fuel: Contaminants in the fuel, such as dirt, rust particles, or water, can clog the pump's filter or damage its internal components. This is less likely to cause outright failure than gradual performance degradation.
* Electrical Issues: Problems with the fuel pump relay, wiring harness, or the fuel pump's own electrical connections can prevent the pump from working correctly or lead to overheating and premature failure. A bad connection creates resistance and generates heat.
* High Fuel Pressure: While less common, excessive fuel pressure (perhaps due to a faulty regulator) can put extra strain on the pump, shortening its lifespan.
* Vehicle Vibration: The constant vibration from the engine and driving can cause stress on the pump, particularly if it's already weakened by age or other factors.
* Fuel pump itself being a low quality replacement: If it was previously replaced, an inferior part could fail more quickly.
In short, a combination of age, poor fuel quality, and electrical problems are the usual culprits. It's hard to pinpoint the *exact* cause without diagnosing the specific failure mode of the pump.
