All You Need To Know About Fuel Sending Units

Intran manufactures over 1,600 SKUs for fuel and electrical systems, which amount to over 8 million parts annually. This includes fuel pump and sender assemblies, as well as many molded plastic parts and end-formed products.

In this article we’ll focus on fuel-sending units and cover everything you need to know about them.

What Does A Fuel Sending Unit Do?

The fuel-sending unit works as the middleman between your vehicle’s fuel tank and the fuel gauge on your dashboard. It ensures that you always know how much fuel is left in your tank. It comprises a float connected to a variable resistor, which measures the fuel level in the tank.

When the fuel level changes, the float moves, altering the resistance in the unit and sending an electrical signal to your fuel gauge. Without a properly functioning fuel-sending unit, you will be guessing how much fuel is left in the tank. If you run the tank dry, you won’t just be stranded; it can also damage other fuel system components.

What’s The Difference Between A Fuel Pump And A Fuel Sending Unit?

Both reside within the fuel system, but they perform very different functions:

• Fuel Pump: The primary function of the fuel pump is to deliver fuel from the tank to the engine. The fuel must be at the right pressure for the fuel injectors to work properly. A malfunctioning fuel pump can result in a rough-running engine.

• Fuel-Sending Unit: The fuel-sending unit measures the fuel level and relays this information to the fuel gauge. The name is a bit of a misnomer, as it is actually a fuel-level reading unit. If it fails or malfunctions, the vehicle will continue to perform as normal, but you won’t know how much gas is left in the tank.

What Materials Are Best For Manufacturing A Fuel Sending Unit?

Given the environment in which they operate, fuel-sending units need to be robust and resistant to corrosion, pressure, and wear. The best materials for manufacturing fuel-sending units include:

• Stainless Steel: Provides resistance to corrosion and durability. It’s a common choice for components exposed to the harsh conditions inside a fuel tank.
• Brass: Used for electrical connectors due to its excellent conductivity. It is also very corrosion-resistant.
• High-Quality Polymers: Some parts of the fuel-sending unit may be constructed using special polymers. These provide lightweight durability and resistance to fuel degradation.

Intran uses the best quality materials to ensure longevity, reliability, and consistent performance. This makes our fuel senders ideal for OEM and aftermarket applications.

How Does A Fuel Sending Unit Work?

The fuel-sending unit is deceptively simple in its design.  The unit consists of three main components:

• Float: A buoyant object that floats inside the gas tank.
• Arm: A metal rod attached to the float. It pivots based on the float’s position.
• Variable Resistor: The arm connects to a variable resistor that moves up and down with the fuel level.

The resistance translates into different voltage signals sent to the fuel gauge. A low resistance when the fuel level is high results in a high voltage signal to the fuel gauge. The opposite happens when the fuel level is low.

How Long Does A Fuel Sending Unit Last?

The moving parts within a fuel-sending unit will eventually wear out, but some can last for the life of the vehicle. However, contaminated fuel, accident damage, or electrical issues can shorten its lifespan. Driving on rough terrain or using poor-quality fuel may result in fuel-sending unit issues.

What Are The Symptoms Of A Bad Or Failing Fuel Sending Unit?

• Inaccurate Fuel Gauge Readings: One of the most common signs of a failing unit is an erratic or stuck fuel gauge needle. It may show a full tank when it’s empty or fluctuate wildly between readings.
• Empty or Full Tank Indications: If your fuel gauge is stuck at empty or full, regardless of the fuel level, your sending unit may be to blame.
• Dashboard Warning Light: If there is a voltage issue in the fuel-sending unit, some modern vehicles may detect a fault, which can trigger a check engine or other warning light.

What Components Within A Fuel Sending Unit Are Most Likely To Fail?

The fuel-sending unit can fail due to a few common issues:

• The float may come loose or become saturated with fuel. This will lead to inaccurate or fluctuating fuel readings.
• The arm may wear out or become loose, which can also cause a false fuel level reading.
• While the above failures do occur, the most common issue with fuel-sending units is the variable resistor. As the arm moves up and down over this part, it eventually wears out, leading to intermittent issues. Electrical issues can also damage the resistor.

Where Should I Get My Fuel Sending Units Manufactured?

If you’re in the market for high-quality fuel-sending units, you need a partner with years of experience supplying OEM-quality components.

Intran is a leading provider specializing in precision-engineered automotive fuel components, including sending units. We have a proven track record of excellence and adhere to the highest quality standards. We are both IATF 16949:2016 and ISO 9001:2015 certified.

Choosing Intran as your manufacturing partner will ensure that every part is manufactured to deliver OEM-level quality, functionality, and reliability. We have over 55 years of experience in the automotive manufacturing business and have produced OE parts for American Motors, Chrysler Corporation, Nissan, and Volkswagen.

Take a look at our wide range of manufacturing capabilities here. If you’d like more information on our fuel-sending units or any other products, contact us here.