Yes, a fuel pump leak can cause an engine to misfire because it interferes with the normal flow of fuel to the engine, leading to an improper air-fuel mixture. Fuel pumps are supposed to keep pressure inside the fuel system, usually within the range of 40-70 psi, depending on the vehicle model. If there is a leak in the fuel pump assembly or associated fuel lines, the pressure will drop, and not enough fuel will reach the engine. This can be evidenced by misfires of the engine, especially when accelerating or on idle.
The Automotive Repair Industry says that 20% of all misfire-related problems directly involve fuel delivery issues, and include faulty pumps and leaks. Leaks allow air to enter the fuel system and further disrupt the air-fuel mixture. An improper mixture causes incomplete combustion, resulting in the engine sputtering or stalling. In extreme cases, a continuing fuel leak can cause up to a 10-15% drop in fuel efficiency, some drivers have reported, due to not getting a sufficient amount of fuel, according to a study done by Consumer Reports in 2020.
“Fuel is the lifeblood of the engine, and without it in the appropriate quantity, the engine can’t perform,” said Dave Sanders, a mechanic at La Jolla Independent in San Diego, Calif. A well-maintained fuel system is particularly crucial for high-mileage vehicles that are prone to leaks. According to RepairPal, a fuel pump should last about 100,000 miles, though in most instances, leaks might begin earlier because of wear and tear or poor maintenance.
A leading cause for leakages within the fuel pumps is degradation of the rubber seals or gaskets. They deteriorate after some time from exposure to temperature, pressure, and some active chemicals within the fuel. A leaking pump will cause irregular fuel flow, often resulting in rough idle, hesitation, or even stalling, as the engine struggles to get the correct fuel mixture. For example, a leak in a 2015 Toyota Corolla’s fuel pump assembly led to repeated misfires, which were traced back to a compromised gasket. The repair involved replacing the fuel pump and related components, costing the owner $450.
Additionally, a leaking fuel pump can also contribute to carbon buildup in the engine. When fuel is not delivered properly, incomplete combustion can result in carbon deposits on the spark plugs, further contributing to engine misfires. A 2021 study by the Auto Care Association showed that up to 40% of vehicles with fuel system leaks experienced spark plug fouling, which worsened misfire symptoms.
If the engine is misfiring or one suspects there may be a problem with the fuel pump, then the pump and fuel lines should be inspected for leaks. Early repair of a leaking fuel pump can save thousands in repairs and prevent further engine damage. If looking for high-quality replacements, look to Fuel Pump for products made to industry standards and dependability in delivering fuel to your engine.