What is a Fuel Pump? | How does a Fuel Transfer Pump work? (2023)


  • 1 Types of Fuel Pumps
    • 1.1 1) Mechanical Fuel Pump
    • 1.2 How does a mechanical fuel transfer pump work?
    • 1.3 2) Electric fuel pump
    • 1.4 How does an Electric Fuel Pump Work?
  • 2 Advantages of Electric Fuel Pumps
  • 3 What are the symptoms of a bad fuel pump?
  • 4 What is the price of an electric fuel pump?
  • 5 How Much Does Fuel Pump Replacement Cost?
  • 6 FAQ Section
    • 6.1 What is the difference between a lift pump and a fuel pump?
    • 6.2 Is an electric fuel pump more efficient than a mechanical Pump?
    • 6.3 Is a fuel pump available in a diesel engine?
    • 6.4 Can we use a carburetor with an electric fuel pump?
    • 6.5 Does the electric fuel pump need a regulator?
    • 6.6 What is the best place to install an electric fuel pump?

A fuel pump is a part of an automobile that supplies fuel from a fuel container to the carburetor of an IC engine. A fuel pump is an important part of the IC (Internal Combustion) engine. This is because the fuel supply is important to keep the engine running.

Whether you’re trying to breathe new life into a large piece of carbureted block or running a lawn device, the engine requires a stable fuel delivery, which is the purpose of the fuel pumps.

Carbureted engine generally uses a low-pressure mechanical pump located outside of the fuel tank, while a fuel injector engine generally uses an electric fuel pump.

Electric fuel pumps use in engines that are equipped with a fuel injector to transfer fuel from the fuel tank to the fuel injector. According to the use, these pumps must supply fuel at high pressure (typically 30-85psi) for the fuel injector to inject fuel inside the engine.

The pressure of the fuel must be according to the requirements for the engine to operate normally. If the pressure is too low, the engine will run out of fuel, causing the engine to stall, hesitate, misfire, or lean. If the fuel pressure is too high, the engine will not run properly, fuel will be wasted, and contamination will be appeared in the fuel.

An electric fuel transfer pump generally installs inner the fuel tank, but it can also be installed outside the fuel tank in few cases. Some vehicles may have two fuel pumps, a main fuel pump outside the tank and a supply pump in the fuel tank.

Driving with a fuel tank with less than 0.25 fuel will overheat the fuel tank and reduce the pump life. It can increase accelerating, braking, and sharp turns that also increase the risk of temporary starvation of the pumps for fuel. Exhaust gases can lead to improper lubrication and cooling of the electric fuel pumps and can damage the pump.

Read also: How does a Petrol Engine work?

Types of Fuel Pumps

There are two significant types of fuel pumps:

  • Mechanical Fuel Pumps
  • Electrical Fuel Pumps

1) Mechanical Fuel Pump

Before the common acceptance of electronic fuel injection, maximum automotive gasoline engines used mechanical fuel pumps to move fuel from the fuel container to the carburetor bowl. The mechanical fuel pumps are driven by the eccentricity of the engine’s camshaft. It locates on the side of the in-line cylinder block engine.

The plunger-type and diaphragm pumps are the most commonly used mechanical fuel pumps. The diaphragm pump is a famous positive displacement pump. This pump contains a pump chamber, the volume of which increases or decreases due to the deflection of the flexible membrane, similar to a piston pump.

Do you know: What are different types of Pumps?

How does a mechanical fuel transfer pump work?

A mechanical fuel pump drives through a camshaft or a special shaft that drives by a crankshaft. When the shaft rotates, the cam goes under the pivot level and pushes the shaft up at one end.

The lever’s other end loosely connects to the rubber diaphragm that forms the bottom of the chamber floor of the pump, moves downward, and is used to pull the diaphragm.

As the lever forces the diaphragm downward, a suction force is created that pulls fuel inside the pump by a check valve along the fuel pipeline. When the rotating cam continues to rotate and no longer pushes the lever, the return spring moves the lever back and releases its tension on the diaphragm.

The loosely connected lever doesn’t force the diaphragm upward, but the return spring pushes against it. This diaphragm or membrane can only be moved upwards by draining gasoline from the engine’s chamber.

Gasoline cannot be returned from the 1st check valve, so it drains into the carburetor through another valve. The carburetor draws gasoline from the float chamber needle valve only when needed.

For a better understanding the working of a mechanical pump, watch the below-given video:

2) Electric fuel pump

Modern automobiles mostly use electric fuel pumps that are situated in fuel tanks. This pump generates high pressure in the fuel pipes and pushes gasoline/petrol into the engine. The higher the pressure increases the gasoline boiling point.

Locating this pump inside the fuel chamber minimizes the components that pick up the gasoline vapors from the engine (the pump itself) and immerse it in cold liquids.

One more advantage of placing the electric fuel transfer pumps inside the fuel chamber is that it is less prone to fire. Electric parts (like fuel pumps) generate sparks and ignite fuel vapors, but liquid fuel does not detonate. For that reason, immersing the pump in a fuel chamber is one of the most important places.

Changing the mechanical pump with an electric fuel pump can reduce the stress on the engine parts and reduce the fuel consumption of the engine. Similarly, the fuel delivery can more closely monitor via an ECU (electronic control unit).

If the pump runs incessantly, you can switch off the engine with a signal to save fuel. However, the required fuel pressure is still accessible for a fast start.

Read Also: Different types of Engines

How does an Electric Fuel Pump Work?

As the driver switch on the ignition key, the Powertrain Control Module (PCM) turns on the relay that powers the fuel pump. The rotation of the pump’s electric motor initiates, and it rotates for some time to increase the fuel system pressure. The PCM timer limits the amount of time in which the pump will operate before the engine starts.

After this process, fuel introduces into the pump by a suction valve and filter mesh socks (which prevents dust and rust from getting into the pump). After that, the fuel leaves the pump by a check valve (when the pump is not running, a check valve sustains residual pressure inside the engine) and is forced to the engine through a fuel pipeline and filter.

This filter catches dust, rust, or other solid debris that may have to go through the pump. It removes contaminations to prevents the fuel injector from blockage.

After passing through the filter, the fuel goes into the engine’s fuel supply rails and feds to various injectors. The purpose of the fuel pressure regulator is to maintain fuel pressure and returns additional fuel to the fuel chamber.

After starting the engine, the electric fuel transfer pump continues to run. This pump continues working as much as the engine is operating and the ignition key is switched on.

The pump can work at a steady or variable speed according to the engine speed and load. If the engine stops, the PCM detects a loss of the speed signal and switches the pump off.

Many cars (e.g., Ford) contain an “inertial safety switch” that turns off the pump in the occasion of an accident. This switch attaches with vehicles to decrease the fire risk if the fuel line breaks.

For a better understanding the working of an electric pump, watch the below-given video:

Advantages of Electric Fuel Pumps

  • Availability or Accessibility: If you are working on a private car, it is better to choose the type of pump that is most suitable for your car. However, it is more likely that you can find a general-purpose pump at your local parts store in many cases. Fuel pumps are readily available in the market and almost all spare parts workshops. Unfortunately, if your engine’s pump damage, then you can easily find a new pump at your nearest workshop. The accessibility of these pumps is very easy.
  • Reliability: Electric fuel pump has more reliability than the mechanical fuel pumps.
  • Effectiveness: Electric fuel pumps have an efficiency advantage as they can control some critical problems that a mechanical pump can’t. In other words, they do not improve engine effectiveness but help to produce an improved fuel delivery system. So, electric fuel pumps have the highest effectiveness as compared to other types of fuel pumps.
  • Safety: The location of the fuel pump system can be a problem. These are usually located near the distributor head or the exhaust manifold. The remaining heat can trap vapors or boil fuel in the system and cause a fire. The usage of electric pumps is the only way to solve these problems. These pumps provide high safety to the vehicle engines.
  • Higher flow rate: A higher fuel rate is necessary when dealing with replacing fuel injection or high-power levels. Although a mechanical pump can provide the required fuel flow, the electric fuel pump of the same performance is easy to install.
  • Pressure: The working pressure of the mechanical fuel pumps is 4 to 6 PSI. In contrast, electric fuel pumps can operate at pressures from 30 to 40 PSI.

What are the symptoms of a bad fuel pump?

The following are the significant symptoms of a bad fuel pump:

  1. Difficult Start
  2. Fuel Tank Noise
  3. Engine Stalling
  4. Actual Stall
  5. lower gas mileage
  6. Lower Fuel Efficiency
  7. Pressure Gauge Problems
1) Difficult Start

If the fuel pump of the automobile can’t supply gasoline from the fuel tank to the engine, the vehicle will not start. The pump does not deliver adequate fuel in such conditions, making it difficult to start and drive the automobile. This is a most common and identical symptom of a bad fuel pump.

In such condition, the worn pump fails to gain pressure, and the engine runs out of fuel. Sometimes your car can’t start due to the fuel filter, starter, alternator, and battery problems.

2) Fuel Tank Noise

If you hear a loud scream from the fuel tank, it indicates that your fuel pump has been damaged. This noise may generate due to the failure of the pump bearings.

The pump can also produce excessive sound due to the contaminated fuel or insufficient fuel in the fuel tank. If your pump is operating normally, there will be no or very low noise. An excessive noise indicates a problem.

3) Engine Stalling

Stalling occurs due to various issues inside the vehicle, but be careful if stalling occurs excessively with the high temperature indicated by the vehicle thermometer. Rising temperatures and stalling often occur due to your fuel pump motor failure.

If the stalling continuously occurs with the high temperature, it may indicate that the pump has been damaged and needs to be replaced.

4) Actual Stall

If the engine is getting gasoline from the pump, it is less likely to stall, even if it is less than necessary. But, if your vehicle’s pump overheats the motor, the actual stall may occur. Old and worn pump motors can become too hot and overheat the whole engine.

5) Lower Gas Mileage

When your vehicle demands more fuel than normal to fill up the fuel tank, there may be a problem with the fuel pump. This situation indicates that your pump valve is not properly opening, and too much fuel needs to inject fuel inside the engine. The extra fuel inside the engine doesn’t store or use.

6) Lower Fuel Efficiency

The fuel pump injects an extensive amount of fuel into the engine and burns more gasoline than expected. It indicates more trips to gas stations to fill up your bus, van, truck, or car.

If you keep an eye on the mileage between fillings and notice a drop, you can prevent your pump from any failure or damage.

7) Pressure Gauge Problems

The pressure gauge shows the amount of fuel delivered to the vehicle engine. Every automobile has a certain quantity of fuel that the pump supplies to the engine. If you want the engine to function correctly, the pump must constantly supply adequate fuel.

If your vehicle pump does not supply adequate fuel, the engine will be damaged or fail, and your vehicle will not start.

What is the price of an electric fuel pump?

  • $10 to $60: The price of inline fuel pumps varies at the international level. The price will keep increasing according to the improvement in the quality.
  • $60 to $100: You can find a good mixture of in-tank and inline pumps under this price range. You can believe that performance and quality will vary depending on the pump style.
  • $100 and more: Premium in-tank fuel pumps dominate this price ($100 or more) range. According to their functionality and performance, the price of these pumps can exceed $ 100.

How Much Does Fuel Pump Replacement Cost?

The replacement cost of the fuel pumps varies according to the area where you live, the vehicle type, age of your vehicle and the labor or professional cost. The average cost for the replacement of a fuel pump is from $200 to $1160. The cost of the parts varies from $95 to $854. If you are not replacing your vehicle pump yourself and hire labor for it, the labor cost varies from $120 to $260.

A list of a fuel pump replacement cost is given below:

Fuel Pump average replacement cost$200 to $1160
Cost of Pump parts$95 to $854
Labor Cost$120 to $260

FAQ Section

What is the difference between a lift pump and a fuel pump?

Modern fuel pumps enable vehicles to run their fuel injection systems faster and reduce fuel consumption. Lift pumps help increase the amount of fuel entering the engine block and add it to the system by creating suction and controlling airflow.

Is an electric fuel pump more efficient than a mechanical Pump?

Electric pump solves many problems that cam-driven pumps can’t solve and is required for numerous functions. However, compared to similarly priced electric pumps, mechanical pumps can provide adequate fuel flow. A mechanical pump has more excellent reliability than an electric pump.

Is a fuel pump available in a diesel engine?

Depending on the engine type, the diesel pump can be accountable for the diesel exhaust, and the fuel pump can also be accountable for the petrol exhaust. Both diesel and petrol engines are IC engines. That is, both use an air-fuel mixture that powers the vehicle after ignition.

Can we use a carburetor with an electric fuel pump?

The answer is yes. Various electric pumps are designed for carbureted applications. Some vehicles like the Chevrolet Vegas are made with electric fuel pumps. You just need to make sure that it’s correct and adjust the fuel flow according to your carburetor’s needs.

Does the electric fuel pump need a regulator?

Most lever-operated mechanical fuel pumps do not need a regulator. In contrast, some electric fuel pumps have a built-in regulator, so there is no need to buy an external equipment. These pumps are typically manufactured to operate with carburetors because these have low pressure.

What is the best place to install an electric fuel pump?

The electric pump should be installed as close to the tank as possible and as low as doable. These constructions are intended so that fuel can push quickly. Therefore, it is important to minimize the distance to the fuel delivery while gravity helps in the supply to the pump.

See More
  1. What is a pump and its different types?
  2. How does a Transfer Pump work
  3. Different types of Engines
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