In an internal combustion engine, surging could also be caused by a malfunctioning fuel pump, in which the engine could rev on its own without the prompting of the driver. This condition results from the inability of the fuel pump to supply a constant pressure of fuel either too high or too low inside the engine. In case the fuel pump does not have enough capability to provide fuel at a required pressure, the air-fuel mixture inside the engine is not balanced, causing incorrect acceleration, hesitation, or surging of the vehicle.
The fuel pump has an operating pressure range that allows the engine to get the right amount of fuel for combustion. This is usually between 30 and 60 psi on most gasoline engines, but variations outside this range may cause disruption in the working of the engine. In the case of a failing pump, the pressure fluctuates, leading to symptoms such as surging. As a matter of fact, a study by AAA revealed that 25% of all engine surging problems were directly related to faulty fuel pumps, while 30% were contributed by fuel delivery problems.
This condition is mostly accentuated under certain conditions in driving, for instance, accelerating or decelerating. When a fuel pump begins to fail, it cannot always supply a continual flow of fuel. Because the engine tries to compensate for lost fuel, this could cause it to surge. According to Ford’s report from 2019, vehicles with failing fuel pumps showed engine surges at speeds over 45 mph, with the problems more severe as the engine’s load increased.
One symptom of a failing fuel pump is hesitation in the engine, particularly when accelerating. If the fuel pump cannot maintain a constant fuel supply, the engine might stall for brief moments or surge, resulting in jerky movements. According to Chevrolet, a faulty fuel pump can cause hesitation as low as 20 mph, but surging is more noticeable at higher speeds. The fuel system does not hold the proper pressure within the vehicle, resulting in incomplete burning and erratic engine behavior.
Surging caused by a faulty fuel pump is not exactly a safety concern but could be a cause of more serious damage to the engine. Due to fluctuation in the fuel supply, it may cause a misfire in an engine, putting stress on various elements like fuel injectors and spark plugs. According to Toyota engineers, the consequences of poor fuel delivery causing engine surging are long-term damages to these components, which might cost a lot to repair. Improper fuel pressure causing an engine misfire has sometimes been related to increased wear in the engine itself, thereby reducing the life of an engine by 20% if left unresolved.
Repair costs regarding a faulty fuel pump that causes surging vary wildly. Replacing the fuel pump can cost anywhere from $300 to $800 depending on the make and model of the vehicle. However, further damage can be much more expensive if the car is still driven on a bad pump, with other potential failures including the ECU, fuel injectors, and fuel lines. A Honda case study showed that vehicles with a defective fuel pump that were not promptly repaired experienced a 15% increase in repair costs due to secondary damage.
In short, a faulty fuel pump can cause engine surging due to disrupting fuel pressure, leading to an erratic fuel supply. It is best for drivers to have their fuel pump inspected for surging, mainly during acceleration or at higher speeds, in order to prevent further damage and improve overall performance of the engine. To know more about fuel pumps, log on to Fuel Pump.