The first signal someone is likely to notice about the fuel pump failing is that he has a more difficult time starting the engine. An inadequate fuel pump could cause insufficient pressure and in return the engine will not receive a proper amount of gasoline. However, as a general rule of thumb, modern fuel systems will require around 40-60 psi to start the engines effectively. If the fuel pump [amazon link] cannot maintain this pressure, it can lead to slow starting or no-start conditions. An average operating pump will fire the vehicle in two to three seconds, if the pumps relies only then a longer crank time of ten seconds or more.
Engine sputters at high speeds A malfunctioning fuel pump that cannot deliver the correct amount of gas the engine requires to remain at full power may cause no-power-like effects, especially while driving at high speeds. Under normal conditions, a good pump will supply the engine with enough fuel to hammer it at 60 mph or higher, but if its on the way out, it can randomly fail. The problem is that if the fuel pressure drops even as much as 10% less than what it needs to be, a huge chunk of performance goes out the window.
Another sign is when your car stalls often If you stall, particularly under heavy load or going uphill this can be a sign of a weak fuel pump. In fact, nearly 25% of vehicle stoppages in a 2017 breakdown report were attributed to defective fuel pumps. At any time the engine may stall due to erratic operation of the pump. This is dangerous, especially if the car breaks down on a highway or in heay traffic.
Another important red flag is erratic acceleration. One of the most common reasons your car wants to hesitate while you press down on the gas may be that something is going on with the fuel pump; it's not able to provide enough fuel fast enough as needed by the engine (make sure you check all this list node items!!!!). A sudden 15% drop in fuel pressure will cause slow or sluggish acceleration, and simple enough that means reduce power and lower fuel efficiency. And that hesitation is usually most pronounced during low-speed driving or at start-up.
If the fuel pump is whining loudly when trying to start your car, that might also be a sign of failing fuel pump. Your pump should function quietly (or you may hear a low-level hum), but if it is on its way out, then you might notice a high-pitched whine or buzz. That sound is likely exacerbated on to the low end of the fuel tank, given that it will require more for any pump to accelerate. On a larger scale, an automotive recall arrived in 2019 which pointed to nois from fuel pumps as an early sign of systemic failure across thousands of vehicles.
And lastly, a sudden reduction in miles per gallon can be an indicator of something more serious, such as a failing fuel pump. So the engine might use more fuel to achieve a certain level of performance, in response to that consider-the-load situation. An (approximately) 10-20% reduction in fuel economy may indicate that the pump is no longer operating efficently. If you monitor your vehicle's average miles per gallon, you might catch this early.
Fuel Pump provides additional information on how to find a bad fuel pump.