Your car’s fuel pump powers your vehicle by moving fuel from the gas tank to the engine, as you might expect.
The fuel pump is well-known for its crucial role in the carburettor and/or injection system, which continuously helps in the vehicle’s fuel circulation.
It is important to learn more about the fuel pump because it is an essential component that keeps your automobile moving. This is why in this reading, we’ll explore what a fuel pump is, its functions, parts, diagram, types, and how it works. We’ll also look at its symptoms, diagnosis, and replacement cost of bad ones.
Let’s begin!
What is a Fuel Pump?
A fuel pump is a part of many liquid-fuelled engines, such as diesel or petrol engines, that moves fuel from the fuel tank to the part that mixes it with intake air, like the fuel injector or carburettor.
Just as said, it is used in an automobile’s engine to transport fuel from the fuel tank to the internal combustion engine’s carburettor or fuel injector.
Low-pressure mechanical pumps that are installed on the engine are frequently used in carbureted engines.
Either high-pressure mechanical pumps located on the engine (for high-pressure direct injection systems) or electric fuel pumps installed within the fuel tank (for lower pressure manifold injection systems) are used in fuel-injected engines.
Some engines don’t even have a fuel pump. Such engines work with a gravity feed system, which involves merely putting the tank higher than the carburettor, can provide a low-pressure gasoline supply for a carbureted engine.
In carbureted bikes, where the tank is often situated immediately above the engine, this technique is frequently employed.
Related: What is Fuel Filter? Its Functions and How it Works
Functions
Below are the functions of fuel pumps:
- Its major function is to pump fuel from the tank into the combustion chamber.
- Fuel is converted into energy for starting the vehicle engine.
- Functions can be divided based on the type of vehicle.
- In injection system vehicles, fuel is pumped from the tank to the injector.
- In carburettor system vehicles, fuel is pumped from the tank to the carburettor.
- Fuel pumps are used in liquid-fuelled engines to transfer fuel from the fuel tank to the intake air-mixing device.
- Carbureted engines use low-pressure mechanical pumps on the engine.
- Fuel-injected engines use either electric fuel pumps inside the fuel tank or high-pressure mechanical pumps on the engine.
Parts of a Fuel Pump
The major parts of a fuel pump include:
- Pump and Gauge
- Electrical Connection
- Tank Vent and Evap Connection
- Fuel Tank Pressure Sensor
- Motor/Pump Assembly
- Pressure Regulator
- Fuel Gauge Float
- Fuel Outlet
- Fuel Pump Reservoir
All these fuel pump part names will be explained in the section of the working principle.
Diagram
Types of Fuel Pump
The various types of fuel pumps include mechanical and electric fuel pumps.
Mechanical Fuel Pump
A mechanical fuel pump is an older kind of fuel pump. This pump is powered by the engine speed coupled to the belt. The camshaft mechanism, which is situated on the cylinder head, is what moves this part in other engines for cars.
These are basically low-pressure fuel pumps; however, they may also be used for high-pressure applications. Their primary function is to move fuel from the tank to the spark-ignition engine’s fuel bowl.
The camshaft, or a dedicated shaft powered by the crankshaft, powers a mechanical fuel pump. A cam moves beneath a pivoting lever as the shaft rotates, pushing it upward at one end.
Electrical Fuel Pump
Electric fuel pumps are the second kind of fuel pump. There is another kind of fuel pump that runs on electricity, which powers the electric motor.
This kind of device is further separated into two subtypes: the standard model, which is frequently found in automobiles with injection systems, and the kind that employs a platinum diaphragm.
These kinds of fuel pumps are typically found in fuel injection systems, which are a crucial component in modern vehicles. To get fuel out of the pump, it generates a lot of pressure.
The explosion might be caused by the fuel igniting within the pump due to the high pressure. Therefore, the electronic fuel pump should be located within the fuel tank and away from the engine for safety reasons.
How Does a Fuel Pump Work?
Fuel pumps, usually low-pressure but sometimes high-pressure, move fuel from the tank to the spark-ignition engine’s fuel bowl. A camshaft- or crankshaft-driven shaft drives a mechanical fuel pump. Cams beneath pivoted levers raise one end as the shaft revolves.
The lever’s opposite end, loosely attached to a pump chamber’s rubber diaphragm, descends and pulls it.
The lever pushes the diaphragm down, creating suction that sucks fuel into the pump through a one-way valve. A return spring moves the lever back as the rotating cam spins farther, relieving its tension on the diaphragm.
A return spring presses on the diaphragm, but the loosely coupled lever. The diaphragm can only rise by expelling fuel from the chamber.
Fuel cannot return through the first one-way valve; thus, it travels to the carburettor through another valve. The needle valve in the float chamber allows petrol into the carburettor just when needed.
In the working of an electric fuel pump, a rod is dragged into a solenoid switch to open contacts to turn off the current in an electric pump.
Fuel enters the chamber when the solenoid pushes the diaphragm down with an iron rod. The iron rod breaks the magnetic current and relaxes the diaphragm pull by forcing apart a series of contacts at its end.
The diaphragm return spring lifts the diaphragm and pushes the rod away from the contacts, which shut, and the solenoid lowers them.
Symptoms of a Bad Fuel Pump
Below are the common signs of a bad fuel pump:
- Noise From the Fuel Tank
- The Engine Sputters or Surges
- Difficulty Starting the Car
- Reduced Gas Mileage
- Stalling at High Temperatures
- Dead Engine
Noise From the Fuel Tank
If the fuel tank makes a whining sound, the pump may be failing. If your fuel pump grumbles, you may be short on petrol or have tank contaminants.
The Engine Sputters or Surges
The fuel pump can be faulty if the engine starts to splutter while you’re driving. The engine performs worse and starts to splutter if the fuel pump is unable to supply a constant flow of fuel to the engine.
You can also notice the vehicle surging when the engine isn’t receiving enough fuel due to a malfunctioning fuel pump.
Difficulty Starting the Car
A malfunctioning fuel pump may be the cause of your car’s inability to start; however, there are other possible causes.
There’s a strong probability that the fuel pump is unable to supply petrol to the engine if the engine turns over when you turn the key but feels like it won’t start.
Continued attempts to start the vehicle without enough fuel can deplete the battery and strain the starting system, necessitating car maintenance.
Reduced Gas Mileage
Consider a malfunctioning or broken relief valve in the fuel pump if you find yourself filling up your fuel tank more frequently than normal. Excess gasoline can enter the engine system if the valve doesn’t open when it should.
Sadly, extra fuel or petrol cannot be stored or used in the engine; instead, it simply burns up needlessly, lowering gas economy.
Stalling at High Temperatures
Engine stalling is frequently a sign of a malfunctioning fuel pump, particularly if the temperature on your car’s thermometer gauge is rising.
The engine must work harder to maintain functioning correctly if the fuel pump isn’t supplying enough fuel. The engine becomes hotter the harder it needs to work, and it may stall to prevent overheating.
Related: What Is A Fuel Injection System? Its Diagram and How It Works
Fuel Pump Maintenance
It is absolutely important to maintain the fuel pump and other car parts. Cleaning the tank on a regular basis, at least once a year, is part of fuel pump maintenance.
Additionally, you must clean the injector nozzle and filter every 15,000 km, as well as the pump every six months.
Although it is normally not required to replace the fuel pump in advance, if the vehicle is undergoing another repair that requires removing the gasoline tank.
Also, if the existing fuel pump has been operating for more than 100,000 miles, doing so might ultimately save time and money.
See a competent mechanic immediately if the fuel pump appears to be surging and then not delivering enough fuel. The car’s fuel system is essential to its operation; therefore, a badly maintained fuel system is harmful.
Replacement Cost of a Fuel Pump
Depending on the vehicle and age, replacing the fuel pump typically costs between $220 and $1,062. Parts range in price from $95 to $854, and labour expenses are expected to be between $124 and $260. Taxes and fees are not included in estimates.
Beyond this, the only expense is your time if you are replacing the fuel pump yourself. A fuel pump replacement is often regarded as an intermediate-level task.
The cost of replacing a malfunctioning fuel pump might range from $400 to $600 if you want to hire a professional. Depending on the mechanic’s skill level and the equipment they happen to have on hand, the actual replacement should take one to six hours.
FAQs
What is the fuel pump?
A Fuel pump is a component used in many liquid-fuelled engines (such as petrol/gasoline or diesel engines) to transfer the fuel from the fuel tank to the device where it is mixed with the intake air (such as the carburetor or fuel injector).
How do you know if your fuel pump is bad?
The car won’t start.
The car sputters or dies while driving.
The engine surges while driving.
You hear whining in the backseat.
You notice lower gas mileage.
How much does a fuel pump cost?
The typical fuel pump replacement cost is $1,000 to $1,300, depending on the vehicle, age, and region. Labor costs range from about $600 to $700, and parts for fuel pump replacement are about $500 to $600. Estimates do not include taxes and fees.
Can you repair a fuel pump?
Unfortunately, most fuel pumps can’t be rebuilt or repaired. If your fuel pump starts to fail, you’ll almost certainly need to replace it with a new one. However, there are some other failing car parts that can mimic the signs of a faulty fuel pump.
