Signs and Symptoms of a Defective Fuel Pump

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The main job of a fuel pump is to move fuel from the storage tank to the engine. It does this by working with several other auto parts. That can make it hard to tell if it’s broken or not unless you know the signs of a broken fuel pump.

The best way to figure out what’s wrong with a car is to listen to it and learn how it normally works, runs, and acts. What does it sound like? What makes noise? How fast does it usually turn? With this knowledge and a careful mind, you’ll be able to tell when the car starts running strangely.

Realizing that the car is hard to start, hard to keep at idle, or has less power is the first step toward admitting there’s a problem and fixing it. Because so many car parts work together and depend on each other, diagnosis is not always easy. It takes a lot of trial and error, and the process of elimination is often used to find the exact cause.

What is a Fuel pump?

A fuel pump is a device that sends fuel from the gas tank through the fuel filter to the fuel rail. A mechanical or electrical system can control it. From there, the fuel is sent to the injectors, spraying it into each engine cylinder’s combustion chambers. In older cars, the fuel from the pump goes to a carburetor.

Fuel Pump Varieties

The gas pump was a mechanical pump on the engine block in older cars. In newer cars, the gas pump is an electronic pump inside the gas tank. Here, we’ll discuss the different kinds of pumps and how they work.

A mechanical gasoline pump employs positive displacement via a plunger or a diaphragm. The pump pulls in fuel, traps it, then transfers that fuel toward the carb and engine, repeating the process.

Electric fuel pump: A modern vehicle’s electronic fuel injection system requires higher pressure, partially achieved by employing an electric fuel pump rather than a mechanical module. Here are a few electric pump examples:

In-tank: Most new vehicles sold today have fuel pumps housed within the fuel tank. This protects the module, and the gas keeps it cold.

An inline pump is positioned between the gas tank and the engine and is mounted within the fuel system track. It is much easier to replace than an in-tank pump. These are frequently installed beneath the automobile or in the engine bay.

Rotary vane pumps, like mechanical pumps, use positive displacement to transport gasoline. A rotor with “paddles” operates off-center within a chamber inside a rotary vane pump. Because it is off-center, it produces a crescent-shaped opening that allows the gasoline to enter. As the rotor spins, the vanes close the small amount of gasoline and release it once it passes through the exit valve. Vane pumps are classified into four types: rolling vane, sliding vane, flexible vane, and swinging vane.

Gerotor: A gerotor pump also uses positive displacement, but it does so differently. There are two interlocking gears in a gerotor pump: a toothed inner gear and an outer ring gear with smooth curving lobes. The inner and outer gears are offset. Small pockets of fuel can thus be captured, compressed, then released as they rotate.

Symptoms of a Bad Fuel Pump

The vehicle will not start.

A lack of fuel is one of the first things to look for when a car doesn’t start. The engine will not start if the fuel pump is unable to provide fuel to it.


If the car starts but runs rough and dies, the engine may not receive enough fuel.

Under Heavy Load, a Car Dies

If you push your car to its limits, whether by hard-driving or transporting extra weight, and the power cuts out, it could be a sign that the fuel pump is struggling to keep up with the driver’s demands.

Inconsistent and Unintentional Acceleration

An automobile may accelerate without input if the amount of fuel is not correctly managed by the fuel pump.

Fuel Efficiency Has Dropped

If you observe your vehicle gulping more gas than usual, the fuel pump may be broken and spend an obscene amount of fuel.

Increased Engine Temperature

If the fuel pump fails to deliver the correct amount of gas to the engine, the engine may be overstressed, resulting in an erratic rise in temperature.

What is simple way to check Fuel Pump

Listening to the sound of a fuel pump turning on is a quick and easy way to confirm if the pump is working. Turn the ignition key to the “On” position, open the fuel door, and take off the gasoline cap (if your car has one) before driving off. Listen for a buzzing sound by placing your ear adjacent to the fuel door and doing so. If you do not hear any audible action, likely, the pump is not functioning properly.

How to keep your fuel pump in good condition

With in-tank pumps, gasoline functions as a coolant as well. If a tank is consistently empty, you are unwittingly exposing your pump to excess heat. Always consistently fill your tank.
Change the gasoline filter in accordance with the manufacturer’s instructions. A clogged filter could result in unwanted fuel system pressure.

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