A bad fuel pump can definitely cause a car to slow down. This part is responsible for transporting fuel from the fuel tank to the combustion engine at the right pressure for for best combustion. Generally, the fuel pressure on most vehicles needs to be in a range of 30 to 80 PSI (dependant on engine specifications). If the pump can’t maintain this pressure and the engine isn’t getting all the fuel it needs (especially under acceleration or heavy load) power and speed both drop off.
A common cause for loss of speed is due to the Inadequate supply of fuel to the combustion chambers of the engine. It disrupts the air-fuel mixture, which is crucial to generating energy. A lean mixture — due to inadequate fueling — leads to a lower power output and a P0087 OBD-II error code, which means that the fuel rail pressure is too low. Drivers near the end of their battery pack frequently report sluggishness and an increasing inability to climb hills or pass traffic.
A 2020 Subaru recall involving more than 188,000 vehicles is an example of the damage that defective fuel pumps can do. The owners of certain older models such as the Outback and Impreza complained of sudden loss of power and an inability to maintain highway speeds. The problem was with defective low-pressure fuel pumps, Subaru said, in a reminder that even a small fault can have a big impact on a vehicle’s performance.
So if you are wondering how a bad fuel pump can slow your speed, it all has to do with how well your engine runs with the amount of fuel that is delivered. Now most modern vehicles require fuel injectors to be calibrated with a throttle body or mass airflow sensor to properly perform. These systems can’t compensate with the pump failure, so speed reduction is noticeable. A bad pump may also result in hesitation when accelerating, especially at speeds greater than 40 mph, because the engine can use more fuel, Car and Driver says.
A malfunctioning Fuel Pump, if neglected, can cause serious issues, such as engine overheating or permanent catalytic converter damage from excess unburnt fuel in the exhaust system. Replacing the pump immediately can avoid these issues, allowing the vehicle to maintain proper speed and efficiency. As auto expert Scotty Kilmer puts it, “A weak Fuel Pump may get you down the road, but it will not keep you down the road very long.”