How to Replace Fuel Sending Unit

What is a fuel sending unit or otherwise called as fuel float?

It is a device attached in the fuel tank of any vehicle that serves as the measuring unit of fuel contained by the tank. 

Its parts are:

    • the float-is the rectangular plastic at the end of the arm that floats over the fuel.
  • How to Replace Fuel Sending Unit-float image 1How to Replace Fuel Sending Unit-float image 2
    • the arm-is the stick rod connected to the registor and holds the float at the end. The stick rod moves up and down as the float at the end does. When the fuel tank is full its position is leveled, and when the fuel decreases the position is slanting down.

How to Replace Fuel Sending Unit-arm or stick rod

    • the registor-is the circuitry part attached to the fuel tank. The registor will send a message through the fuel gauge that the fuel tank is full, halfway, or empty.

How to Replace Fuel Sending Unit-registor


Last week when I went to the refilling station for an oil change and the vehicle was lifted up I noticed that the fuel tank was quite moist with thick accumulated dirt. I suspected that there is something wrong with it.

The Importance of Fuel Sending Unit

The fuel sending unit is very necessary for the operation of the vehicle every time it is used. It measures the volume of the fuel you have set in the fuel tank. It reminds the driver of how long the distance it takes before the fuel is unavailable. It calls for an action if it’s time or not yet time to refill for fuel.


How to Replace Fuel Sending Unit-fuel tank image 1How to Replace Fuel Sending Unit-fuel tank image 2

Fuel Sending Unit Issues Must Be Fixed 

Once you noticed there is something abnormal you have to fix it immediately. There are two things this unit will save you if in proper condition.

One, it will save you time when you go for your business and the fuel sending unit will tell you through your fuel gauge that you needed to refill before you go for a long journey on areas where there are no available refilling stations.

Imagine when you run out of fuel on areas where there are no fuel refilling stations. You are going to leave your vehicle and look for fuel. There are a lot of inconveniences it will bring when you run out of fuel.

Two, it saves you from additional expenses of fuel due to leak.  A defective fuel sending unit seal will allow dripping when you drive and the vehicle shakes every time and then. It may also allow fuel dissipation during a hot day drive.


How to Replace Fuel Sending Unit-fuel tank image 3


As you can see the rubber seal is melted. It’s actually not original but an improvised replacement from an interior tire.


How to Replace Fuel Sending Unit-fuel tank image 4


How to Replace Fuel Sending Unit-image 5



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There is one bad thing here, it is the use of screw to fasten the fuel sending unit into the fuel tank. Some of the screws are already loose threads. We replaced it with bolts with nuts and are installed right side up in order for the nut to be threaded with the bolt.


How to Replace Fuel Sending Unit-fuel tank image 8How to Replace Fuel Sending Unit-fuel tank image 9


I created a video to illustrate how we replaced the unit. Please watch but please use the proper tools to tighten nuts. I’m happy to show you how that fuel sending unit was fixed. You may have another way of doing it but the principle of having that small part can make a difference.

How to Replace Fuel Sending Unit part 1

How to Replace Fuel Sending Unit part 2


10 thoughts on “How to Replace Fuel Sending Unit”

  1. Interesting post on what the fuel sending unit is all about. Never actually knew about it or what it was called. I understand how the fuel sending unit works and how it does with the fuel float but what I’m confused about it how it melted? Was it a risk to catch fire? Thank you.

    • Hi! Thank you for your comment. The reason why it melted is that the rubber seal they used when they repaired was not original but it was just an improvised from an interior tire. That kind of rubber melts in contact with diesel. You cannot buy a repair kit for that, you have to buy the whole unit even the other parts of the unit are working. I think it would not be a cause for fire unless someone would intentionally ignite it since it’s diesel, however, fuel dissipates due to the movement of the vehicle every time it’s driven.

  2. It is very nice to be able to learn how the fuel sending unit works. I have never heard of anyone talk about this before but it is very nice. I must say that I am very fascinated with how it can send the information through the meter in the car. I will go on to watch the video on how to fix it myself. That is going to save me some money of taking it down to the repair shop.

    • Thanks, John. I would say even me, I cannot fully understand how this unit can communicate with the fuel gauge through the registor. It’s enough to receive the message it sends to us that we needed to refill our tanks along our way.

      Since I noticed that something was wrong why the fuel tank accumulates dust and it doesn’t dry, there must be something to be fixed.

      Thank you for dropping your comment. Please go watch the video. It’s not a perfect one but it can give you the message on how the thing is done.

  3. I have never really understood how the fuel sending unit works before but through this explanation, it looks pretty simple to me. I find that there is nothing so hard about it and that there are ways to replace it when it is faulty. I like that you can tell us the reasons why the fuel sending unit is very important to us. Nice post you have here.

    • Thank you, Henderson for your honest comment. It’s really simple to do but what made it complicated is the use of screws with no threads of the fuel tank.  They just hope the screw will make its way but because of overtightening, they got loose.  We thought of bolt and nuts so it’s better and you have no worries it tightens and grips the rubber seal properly.

  4. I watched the video attached to this and I really found it to be rather great and worth keeping So thoughtful of you to share this informative post ere. At first I felt i should stop reading since I could not resonate well at first with the fuel sending unit or possible replacement but then, when I checked the videos out, they make perfect sense. Thanks for sharing here. It is really a knowledge that everyone would find worthy. 

    • Thanks, Rodarrick. I cannot blame you if you were not able to understand the first paragraphs because of grammar and confusing statements. I was able to go back and edit it.

      Thank you for appreciating the videos. I know they are not as good as others have produced but it carries the message we want to convey.

      This issue is so rare and I know the modern vehicles are equipped with better parts. But who knows this experience can happen to anyone. It’s good you came across with this and I thank you if you would share it.

  5. Hello Accad!

    This is a useful post for people who drive cars, so that if they go into such issues, your guide will be helpful to them – especially when we talk about such an important part like the FSU. If this piece gets damaged, it needs a quick replacement! No one wants to run out of fuel suddenly, without any warning, while they are on the way.

    Car drivers should really master some mechanical techniques, so that they can take care of their cars by themselves.

    Best regards,


    • Yes, Peter. Who knows there are people having this kind of fuel tank that is poorly designed. I know the new vehicles of today are equipped with good designs but the thing is that every vehicle has this fuel sending unit and when they run defective they should be given immediate attention. We cannot discredit the role that it contributes to the whole operation of the car.


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