A bad fuel pump can lead to an engine misfire by interrupting the clean and consistent flow of fuel required for ignition. If a fuel pump is unable to supply the necessary pressure, then an engine may not get enough of its required fuel and will thus run less-than-stable or experience misfires; those problems tend to occur most notably at high-speed cruising and/or under hard acceleration. Most fuel pumps are designed to deliver a certain volume of gasoline at this same pressure, but often they fall short — leading to engine hesitation and sputtering if it is not in that 30-80 psi range.
Diagnosing a fuel pump failure can be difficult, as misfires from this issue may only occur off and on These misfires might be accompanied by other symptoms, like having trouble starting the car, decreased fuel efficiency and even stalling as evidence of an erratic supply. This also means that vehicles with fuel injection systems—systems which need a very specific amount of gasoline in the chamber before being ignited and require precise timing to operate efficiently—are more likely to have running problems if their electric fuel pump efficiency falls off.
Mechanics always tell me that the main cause of engine hesitation is fuel pump failure if other systems (e.g., ignition and air intake) are okay. A report published by Automotive News in 2021 stated that of all engine misfire cases for fuel-injected vehicles, 15-20% are the result of a problem with fuel delivery system and frequently traced back to an issue caused by the failure of the pump. Regular maintenance, like changing the fuel filter every 30k miles should decrease pump-related problems by providing cleaner delivery of gas and decreasing wear on the pump itself.
Depending on your vehicle, a failing fuel pump would cost between $400 to $700 if treated by the mechanic especially since labor can really be expensive. Early symptoms should be watched for, and if an issue is suspected with the fuel pump it deserves attention in order to prevent broader engine troubles leading to misfires that can affect long-term overall health of a vehicle.
To learn more about avoiding engine misfires and learning more about the fuel pump affect on car performance, read this article that delves deeper into how pressure impacts fuel pumps as well as what you should know for keeping them in proper working order.