Fuel pump: operation, prices, breakdowns and checks

electric fuel pump

La electric fuel pump It is an element of great importance in our vehicles. It first appears in the 80s, when injection systems arrived electronics. Since then, it has been mounted on most cars and fulfills a fundamental function: it is the responsible for pumping fuel to get it out of the warehouse and put it through the gasoline filter.

Formerly the gasoline pumps were mechanical, since there were no electrical components in the motors. In these, a mechanical component was necessary, usually a camshaft or a special shaft that was crankshaft driven. The other end of the lever was attached to a diaphragm that made the necessary suction to push the fuel. After this review, we will get to know electric pumps in depth.

Electric fuel pump operation

Electric fuel pump operation

The electric fuel pump, like the mechanical one, also works thanks to a diaphragm. The main difference is that instead of being driven by a camshaft, it is a electromagnetic switch (solenoid) the one that exerts that pull. the solenoid attracts an iron rod and pushes the diaphragm down, causing fuel to enter the chamber.

When it reaches the end of the iron rod travel, the electromagnet current is broken and pull on the diaphragm ceases. Then it rises by the action of a return spring and at the same time moves the rod away from the closing contacts. This makes the solenoid push back the rod and diaphragm down again.

Related article:
Fuel Tank Vent Valve

Features of electric fuel pump

Electric fuel pumps normally work with a voltage of 12V. They are usually installed in the inside fuel tank or in the vicinity of it. The mechanical pumps were installed in the engine, since they had to facilitate the mixture with the air that was made in the carburetor. One of the main advantages of electric fuel pumps is their small size and lightness. In addition to that, having fewer mechanical components, they are usually more reliable.

The fuel pump supplies fuel to the system.

Also its efficiency, well above the mechanics. An electric fuel pump is capable of working at a pressure between 3 and 4,5 bar, although there are some that reach up to 5,8 bars. The mechanics did not reach even a bar of pressure. They are safer, since the Electronic Control Unit (ECU) controls power to electric pumps. It also has the advantage of not overheat to be inside the tank.

In addition to this, electric fuel pumps they have to withstand very demanding working conditions, given the delicacy of its function: to supply a highly flammable liquid. For example, they must work just as well whether the gasoline is at a high temperature or very low. They must also be prepared for different types of gasoline, even if they have additives from the oil companies or other companies.

Related article:
How does a gasoline engine work? Key phases and components

Possible faults in the electric fuel pump

electric fuel pump

Regardless of the quality of our fuel pump, its lifespan will be affected by a number of components. The use of gasoline with foreign particles, rust or improper use of alcohol or methanol will shorten its life. Also maintenance plays an important role, so the gasoline filters should be changed when appropriate to prevent them from becoming clogged.

We leave you a series of tips to extend the life of the fuel pump electrical:

  • There is always gas in the tank. Do not trust the level indicator on our instrument panel if the vehicle is very old, as it can give an erroneous reading. Do not rush the fuel tank, because impurities can get inside the fuel pump and damage it.
  • When a pump is replaced of damaged electric gasoline will be important to clean the fuel tank and lines. Safety precautions must also be taken to avoid any type of accident, for this it is best to follow the manufacturer's instructions.
  • Before installing the new pump in the reservoir check its operation. Something that is achieved by passing current through the system, to see if the solenoid moves the metal rod and correctly pushes the diaphragm. When de-energized by the return spring, it must be able to return it to its place without anything obstructing the movement.
  • To finish this review of the electric fuel pump, we want to emphasize one of the tips. Although it is the simplest, it is of great importance that we do not circulate continuously with the car in reserve. As the pump is housed in the tank if it is empty there will be no fuel to cool the pump. This could lead to overheating and possible breakdown, leading to other faults in the injection system.

electric fuel pumps

price of a fuel pump

If you have to replace the fuel pump of your car, you should know that its price is usually found between the 70 and the 150 euros. Although they can be found more expensive if we are talking about a car in the premium segment or higher.

The installation of the new pump usually takes around a similar price to the same. Although that can vary quite a bit depending on the price of workshop labor and the model in question. There are those in which it is not so easy to do it and it is required to disassemble and assemble more parts.

Check for faulty fuel pump

Check if there is voltage to the fuel pump.

To check pump operation give the starter switch without actually starting the engine. Then you will hear buzz pump running for about two seconds, which is how long it takes to pressurize the fuel system to readiness.

In case you don't hear the buzz Check if current is reaching the plug of the electrical power supply wiring of the pump. Two options:

  • If there is no reading of the voltage required by the pump, check the circuit until you find where the current flow interruption is. It may be due to damaged cables, poor contact or sulfation of the connections.
  • If there is a voltage reading, measure with an ohmmeter the continuity of the electric motor at the pump terminals. If the resistance reading is high or infinite, the pump is damaged.

In the following video you can see how to do it:

The role of the fuel pump in the fuel system

Electric fuel pumps are just one of the elements that an internal combustion engine uses to work. In fact It is part of the low pressure fuel system., which is responsible for removing the gasoline from the tank, passing it through the filter and bringing it closer to the power train in a dosed manner. Hence it works in conjunction with the fuel filter, a dosing valve and a pressure regulator.

Not to be confused with the high pressure fuel pump of an engine direct injection, as this is part of the high pressure fuel system. As its name suggests, it ensures that injectors receive gasoline at about 50 or 100 bar, instead of the 3 to 4,5 bar applied by the electric fuel pump.

The fuel pump is only one element of the fuel system.

If this were not so, gasoline would not reach the combustion chambers with enough pressure to spray correctly. That is to say, sufficiently diffused in the air so that it burns as best and as soon as possible. That way you gain in fuel use and therefore efficiency.

Images 3 and 5 – mroach, Arthur Becker Simões


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      Fabian Martinez said

    I have a problem with a 2000 ford contour. About a year ago I changed the fuel pump, and about 2 months ago it failed me again, so I took it to the mechanic again. We changed the pump and after a few days it started to lose power and pitch when accelerating. I took it to the same mechanic again and he told me that it's probably the EFI system so I'll have it cleaned, but I still have the same problem. I do not know what to do. Now he tells me that it is a sensor, but I have already spent enough and the truth is that I am losing credibility in it. The question: Can it be the sensor of what? or it could be something else. Please help me.

      cease said

    Good morning, friend, I have a ford, f-150 fx4, 2005, cab and a half 8cc v5.4 engine, the problem is the following, when the truck is just started and you drive it at 2000rpm or 3rpm or more it works excellent, but After a certain time of turning it on when driving it, when you go over 2000rpm or you want to accelerate much more to run, it starts to tremble and tries to turn itself off, having a hard time reaching high speeds. I put the scanner on it and they told me that the gasoline filter was dirty, I replaced it but the fault still persists. What could it be? They told me it could be the harmful gasoline pump, is that true?
    Or check the gas tank to do maintenance and change the battery? I would appreciate your answer brother, since I don't want to run the risk of being unnecessarily messed with and less by guessing, as some mechanics do, who are unaware of the fault and what they do is invent to get money from you, thank you very much

      Xavier Cordero said

    How do I disconnect the injector fuel feed line from a 99 Grand Cherokee 5.4 8CLV? I know that a special tool is needed but I do not have such a tool, what other alternative do I have to disconnect it???

      eleazartoledo_vazquez said

    hello, I have a question, I happen to have an American Nissan pickup model 86, Z24 four-cylinder engine, 8 spark plugs and hitachi double-throat carburetor. what happens is that I have changed the fuel pump about five or six times in four years
    I have taken it to electricians, mechanics, electromechanical engineers and no one has been able to fix that detail for me, the pump suddenly stops sending gasoline to the carburetor and therefore the truck turns off, about 8 months ago I decided to connect the gasoline pump directly to the battery terminal with a power switch (switch) on the board and since then it has not given me a problem, I would like to know what risks this would cause or if there is no problem with it continuing like this? I will appreciate your answers.

      Luis said

    Good day to all, I have a concern from Colombia: I have a Chevrolet Swift model 95, this after turning it on after approximately 20 minutes turns off, the mechanic tells me that it is a dirty carburetor problem, it has been washed and the gaskets changed on more than 3 occasions and the problem persists, the strange thing is that the temperature of the car does not rise, and after it turns off and cools down, it turns on without problems, and after approximately the same time it presents the same fault. I thank you in advance for your valuable collaboration and your attention.

      Archimedes Colmenares said

    Good evening, I have a 4x4 blazer. It has a problem with the gasoline pump. It turns on but suddenly it turns off. They tell me that the pump heats up and turns on only when it cools down. Please, thank you for guidance.

      louis miranda said

    Hello, my car has a 200 ford engine, I want to adapt that pump to it, if I can install it, thank you.

      rafael said

    good afternoon, I have a 2005 ecoesport, for a few days, I smell gasoline, I look at the tank and it doesn't leak, but if there is moisture in the tank, the cap is perfect, the filler duct too, then fill the tank , and when I turned it on it started to spill the gasoline, I looked below and the spill is coming from the top. Question what could be happening?
    Thank you for your answers.

      Ramphi Torrealba said

    good I don't get enough voltage to the fuel pump I tried with a tester each of the males that come out of the pacifier that reaches the tank lid connector and the voltage that reaches the float males have a voltage of 11,60 and those that go to the fuel pump have 0.004, what can I do