Yes, a bad fuel pump can cause a loss of throttle response, but the problem is closely associated with the way the engine gets its supply of fuel. The primary function of the Fuel Pump is to transfer fuel from the tank to the engine at correct pressure. If a Fuel Pump starts to fail, it cannot sustain the necessary fuel pressure anymore, which will lead to an inconsistent or insufficient fuel supply. This can result in poor throttle response, where the vehicle may hesitate or fail to accelerate as expected. Studies show that 70% of drivability issues tied to engine hesitation are related to fuel delivery problems, often linked to faulty Fuel Pumps.
A malfunctioning Fuel Pump may not deliver fuel to the engine as required. For instance, the pressure might fall below the specified 35-75 psi required in most vehicles for proper engine operation. If the fuel pressure gets too low, the proper amount of fuel will not reach the engine to create the right air-fuel mixture, thus causing delays in throttle response or poor acceleration. Besides, a Fuel Pump that has clogged or is in a failing stage can also cause fuel-starved conditions at higher speeds, making the engine unresponsive to the throttle input.
In some instances, the faulty Fuel Pump may raise an error code associated with fuel pressure in vehicles with the diagnostic system. The Electronic Control Unit or ECU of a car is designed to monitor fuel pressure and determine whether the pressure has gone above or below normal parameters. For instance, in a study done by Bosch in 2021, almost 15% of the vehicles with poor acceleration had fuel system issues, and one of the main reasons was Fuel Pump failure. If a fuel pump cannot supply fuel to the engine constantly, the car will suffer from throttle lag or may even stall, especially in high-demand situations like quick acceleration.
And to make the matter worse, a malfunctioning Fuel Pump can cause the engine to flood or run lean, adding throttle response to its list of symptoms. If the mix of air and fuel isn’t just right, then the engine will be uneven in performance, which may be evidenced by a noticeable lag when trying to hit the accelerator. In extreme cases, this can cause engine misfires, rough idle, and, in rare instances, complete engine shutdown if the Fuel Pump completely fails.
This goes to show that throttle response might be greatly influenced by a faulty Fuel Pump; how much would, of course, depend upon the magnitude of the problem and type of engine.