Mechanical or electrical problems are quite common and can lead to a slow fuel pump One of the most common reasons is a blocked fuel filter that limits the necessary amount of fuel to be provided to the engine. The filter is a sandpaper, the fuel pump makes a callous with running extra mile to push fuel through the blocked filter and this adversely affects its efficiency. This could slow the pump down by up to 30% or more if its filter is completely clogged. Perhaps the fuel pump is designed to deliver 60 psi but only achieves 40 psi when obstructed by a dirty filter, leading to sluggish engine response and poor acceleration.
Fuel pump operation can be slow because of electrical problems, for example a weak or corroded connection. Fuel Pump — A fuel pump needs a steady flow of electricity to work properly. This slight rpm reduction due to voltage drop, even 10%, can be just enough to slow the pump and cause a problem. For example, in 2018 an automaker had to issue a recall on a line of different vehicles because problems with the wiring harnesses were preventing consistent power delivery to the fuel pump, causing reduced performance and even stalling.
Old fuel pump: An old fuel pump is also likely to operate at a much slower rate. The internal parts of a pump like the motor or even gears can eventually wear out, and it will not be able to maintain a steady flow of fuel. Fuel pumps apt to decay once the distance reached 100,000 miles or close of 150,000 mile. Although it is generally not as bad as that, especially at higher speeds, towing heavy loads or driving for long periods at highway speeds will result in fairly common drops of 10 and even 20 percent efficiency.
Slow fuel pump performance may also be due to debris buildup in the fuel tank. When this happens, sediment and contaminants found in the fuel can come in direct contact with the pump's internal parts causing damage to the pump cycle making it slower. Anywhere from 15-20% reduction in fuel flow can result, and this exhibits itself with slow acceleration or the engine will even die when under high load conditions. By keeping your tank over one-quarter full you can make sure that if anything were to get into the pump, there is additional fuel in the tank to prevent it from getting sucked up.
A dying battery or alternator can lead to a low voltage situation that will slow down the fuel pump. Fuel pumps normally run on a constant 12 volts to be able to function at the top of their capabilities. At 10 or 11 volts, the fuel pump may drop output by some 10%, resulting in modest engine power loss and a slower, angrier throttle. But as a 2019 news report made clear, many vehicle breakdowns were blamed on alternators that failed — and in so doing not only prevented the electrical systems from maintaining output but also kept fuel pumps from operating properly.
Incorrect Fuel Type Finally, the wrong fuel type may also impact the speed of a pump. That was particularly problematic for E85, an ethanol blend that's up to 85 percent ethanol and as a high-octane alternative fuels can be more corrosive to some types of fuel pumps—especially in older vehicles never designed for high ethanol content. This corrosion builds up over time and is responsible for reducing fuel pump speeds by as much as 25%, diminishing the overall performance of the pump.
To learn more about how to diagnose and solve fuel pump problems, head on over to Fuel Pump.