A faulty Fuel Pump can cause hesitation in a car due to improper fuel delivery to the engine, which disrupts the proper air-fuel mixture required for smooth combustion. The Fuel Pump is responsible for transferring fuel in the tank to the engine with constant pressure. When the Fuel Pump starts to fail or malfunction, it may only be able to provide lower pressure fuel or in inconsistent quantity, which may cause the vehicle to hesitate upon acceleration. This is most noticeable when the car is first accelerating, which requires a quick and smooth application of power.
For example, if the Fuel Pump operates at a pressure that is too low, not enough fuel may be supplied to the engine under instant high-demand situations, like when accelerating from a stoplight or merging onto a freeway. One test by Car and Driver observed that a Fuel Pump operating at lower than optimal pressure could cause hesitation by as much as 30-40% during acceleration, especially in vehicles with fuel systems that rely on high-pressure delivery-such as turbocharged or fuel-injected engines.
This would be a perfect example: Consumer Reports gives the case of a malfunctioning Fuel Pump in a 2015 Chevrolet Malibu, which was causing hesitation upon acceleration, mainly when the car is running at low speed. The fuel pump wasn’t able to hold up the pressure as it was supposed to. Replacing the pump did the trick to bring back the performance of the car.
“Fuel delivery issues are one of the primary reasons for engine hesitation,” says Dave Stewart, an automotive technician at AutoFix Service Center. “When the Fuel Pump can’t keep up with demand, the engine stumbles because it’s not getting the right amount of fuel when it needs it most.”
Further, a study by AAA found that over 15% of engine hesitation problems are related to the fuel system, with a substantial percentage of those being directly related to faulty or malfunctioning Fuel Pumps. These pumps, especially if they are old or clogged, fail to provide the necessary flow rate, resulting in misfires or stuttering acceleration.
This would also include a faulty Fuel Pump that can cause air-fuel mixture imbalances; either too much air or not enough fuel, and vice versa. This results in the engine misfiring and essentially hesitating or jerking when trying to accelerate. This is more noticeable with higher-mileage vehicles where the Fuel Pumps can become clogged from debris or dirt over time, further hindering the fuel flow and contributing to hesitation.
“Your car hesitating is a sign that the engine isn’t getting the fuel it needs,” explains John Wilkins, a senior technician at Precision Auto Repair. “Sometimes it’s as simple as a clogged Fuel Pump filter or a weak pump, but in other cases, it could be a more serious fuel delivery issue.”
If a fuel pump completely fails, the car won’t start at all, but in most cases, the pump keeps running on an intermittent basis, supplying enough fuel to start the car but not enough to allow smooth acceleration. Over time, these problems can get worse, leading to more pronounced hesitation or stalling.
Replacing the faulty Fuel Pump with a reliable, high-quality unit is a quick and effective solution that can restore normal vehicle performance and eliminate hesitation. For instance, a high-performance Fuel Pump will ensure that fuel is delivered at the correct pressure and volume, preventing hesitation during acceleration and improving overall engine response.
If you’re facing hesitation issues with your car, a replacement Fuel Pump could be the key to restoring smooth acceleration and eliminating performance issues.