Fuel Pump Or Sending Unit: When To Change And Why

Whether or not you should change your fuel pump or sending unit depends on a number of factors. Firstly, it is important to understand the difference between the two. The fuel pump is responsible for transferring fuel from the tank to the engine, while the sending unit is a component of the fuel pump that monitors the fuel level and sends this information to the fuel gauge. If your vehicle is struggling to start or is not starting at all, it could be a sign of a faulty fuel pump. On the other hand, if your fuel gauge is not sensing the correct fuel level, it is likely an issue with the sending unit.

Some vehicle models have the fuel pump and sending unit integrated into a single assembly, so replacing one often means replacing the other as well. However, it is possible to replace just the sending unit in certain cases, especially if the fuel pump is still functioning properly. It is worth noting that replacing just the sending unit can be more challenging and may require removing the entire fuel pump assembly for access.

Before making a decision, it is recommended to consult with a trusted mechanic or a specialist forum for your specific vehicle make and model. They can provide guidance based on their experience and knowledge of common issues with particular vehicles. Additionally, they can advise on the availability of replacement parts and the level of difficulty in accessing and replacing them.

Fuel pump and sender the same unit?

The fuel pump and sender (or sending unit) are not the same, but they are part of the same assembly. The fuel sending unit is used to measure the amount of fuel in the fuel tank and communicate the fuel level to the fuel gauge on the vehicle dashboard. The fuel pump, on the other hand, is responsible for pumping the fuel to the engine. While they are separate components, they are often sold as a single unit and can be replaced together.

In some vehicles, the fuel sending unit is attached to the fuel pump assembly, while in others, it is a standalone unit. However, both types of sending units have the same three components: a float, a metal rod or arm, and a variable resistor. These components work together to measure the vehicle's fuel level and relay this information to the fuel gauge. The float, made of a buoyant composite or foam, sits on top of the fuel in the tank and is connected to the metal rod or arm, which pivots as the fuel level changes. This movement is transmitted to the variable resistor, which adjusts the amount of resistance voltage encounters. The variable resistor then sends an electric current to the fuel gauge, which displays the fuel level accordingly.

When it comes to replacing the fuel sending unit or the fuel pump, it is important to diagnose the issue accurately. A faulty fuel sending unit can cause the fuel gauge to read incorrectly, such as showing the tank as empty when it is full or vice versa. In some cases, the fuel gauge may become stuck on full or fluctuate between empty and full due to a faulty resistor or mechanical failure. To confirm the issue, it is recommended to perform tests before replacing any parts.

If you need to replace the fuel sending unit, it is worth considering whether to replace the fuel pump at the same time. This decision may depend on factors such as the accessibility of the pump and the age of the vehicle. If the fuel pump is difficult to access, it may be more convenient and cost-effective to replace it along with the sending unit. Additionally, if your vehicle is older, it may be advisable to replace both components to ensure optimal performance and avoid potential future issues.

When to replace the fuel pump?

The fuel pump is an essential component of a vehicle, delivering fuel from the tank to the engine. Usually, fuel pumps are reliable and long-lasting, but occasionally they need to be replaced. Here are some signs that indicate when it's time to replace your fuel pump:

Warning Signs of a Faulty Fuel Pump

• Engine Struggles to Maintain Speed: The engine may feel like it's "choking" and not able to maintain a consistent speed. This may give the impression that the vehicle is out of fuel, even though the gauge indicates otherwise.
• Engine Overheating: A failing fuel pump can overheat, causing the engine to overheat as well. The vehicle may operate for a short period (15-30 minutes) before stalling. After cooling down, the engine may run again but will likely repeat the failure as it heats up.
• Sputtering, Noises, and Backfires: Electronic fuel pumps typically don't make noise unless they start to fail. An inconsistent fuel flow can lead to internal engine problems, causing hesitation during vehicle startup or acceleration.
• "Check Engine" Light Illuminates: Any of the above issues may be accompanied by the "Check Engine" light turning on.
• Engine Won't Start: If the vehicle struggles to start or doesn't start at all, it could be due to a faulty fuel pump that is damaged or clogged.
• Car Sputters or Dies While Driving: A faulty fuel pump can cause low pressure, resulting in the engine not receiving the required fuel and air mixture for combustion. This may be more noticeable during acceleration or when the vehicle is under stress, such as towing a heavy load or driving uphill.
• Engine Surging: A failing fuel pump can send too much fuel to the engine, causing the vehicle to surge, repeatedly picking up and dropping speed unintentionally.
• Whining Noise from the Fuel Tank: A healthy fuel pump makes a low, barely noticeable humming sound. If the pitch increases significantly, it could indicate a problem with the fuel pump.
• Decreased Gas Mileage: A bad fuel pump can lead to poor fuel efficiency due to damaged or worn components allowing excess fuel into the engine.

Maintenance Tips for Fuel Pump Longevity

To ensure the longevity of your fuel pump, consider the following maintenance tips:

• Keep your gas tank at least a quarter full. Gasoline acts as a coolant for in-tank fuel pumps, and running on low fuel levels can increase heat and shorten the lifespan of the pump.
• Perform regular fuel system maintenance, including inspections and replacements of fuel filters when necessary.

Replacement Considerations

If you suspect a faulty fuel pump, it is best to have your vehicle inspected by a qualified technician. The replacement process can be moderately complicated and typically involves removing the fuel tank if there is no access panel in the passenger compartment. The replacement cost can range from $1,000 to $1,300, including labor and parts.

Fuel gauge issues

A faulty fuel gauge can be extremely frustrating and may leave you stranded on the road. The fuel gauge system consists of two main components: the sending unit, which is placed in the fuel tank, and the gauge, which is installed on your car’s dashboard. The sending unit receives the amount of fuel and transmits it to the gauge through an electrical impulse. When everything is in order, the gauge will show the user how much fuel is in the tank.

Common Indications of a Defective Fuel Gauge

• Inconsistent readings: If your fuel gauge is erratic, jumping up and down, or not in sync with the actual fuel level, you have a problem. For example, the gauge may indicate that the tank is full when it is only half full, or it can read half full and immediately become empty.
• Stuck on full or empty: At other times, the gauge can become stuck and your tank will appear full or empty when in fact, it is not. This problem makes your fuel gauge unreliable.
• Fuel light flashing: If the fuel warning light illuminates, even if you have just filled your tank, or if it blinks erratically, then it means that there is a problem with the sending unit or the gauge. You should not ignore this warning light and get your car checked.

Troubleshooting a Non-Working Fuel Gauge

• Check for wiring issues: Inspect the wiring for the fuel sender unit and the gauge to see whether it is loose or corroded. This task usually requires the assistance of a qualified mechanic who can check the wiring and connectors to ensure that none are damaged.
• Inspect the sender unit: Since the fuel sender unit is one of the common causes of failure of the fuel gauge, you should have it checked and tested. If the float is not moving or is broken, the unit will need to be fixed or replaced. This usually involves removing the fuel tank to access the sender unit.
• Test the gauge: If the wiring and sender unit are both functioning correctly, the issue may lie with the gauge itself. A mechanic can check if the gauge is functioning properly or requires replacement.
• Replace fuses: If the problem is due to a blown fuse, simply replacing the fuse should resolve the issue. Refer to your vehicle's owner’s manual to locate the fuses and determine the correct type to use.

Should I Change the Fuel Pump or Sending Unit?

If your fuel gauge has stopped working but your engine is still receiving fuel, the issue is likely with the sending unit rather than the fuel pump. In some vehicles, the sending unit and fuel pump are part of the same assembly, so you may need to replace both. However, it is possible to replace just the sending unit, depending on the make and model of your vehicle.

Fuel pump access

For example, in some Ford vehicles, the sending unit and in-tank pump are part of the same assembly. To replace the sending unit, you would need to remove the whole assembly from the fuel tank, which involves dropping the tank.

If you are accessing the high-pressure fuel pump, make sure you consult the appropriate service information and relieve the system pressure beforehand. Failing to do so can be dangerous as direct injection fuel systems are under extreme pressure.

If your vehicle has a rear seat access panel, you can access the fuel pump by lifting the rear seat and removing the access panel. If your vehicle does not have an access panel, you may need to remove the rear seat completely to access the fuel pump.

In some cases, you may need to remove the fuel tank to access the fuel pump. This can be a more difficult process and may require specialized tools and equipment. Always refer to your vehicle's repair manual or seek the assistance of a qualified mechanic if you are unsure about how to access the fuel pump in your vehicle.

Fuel pump brands

When it comes to fuel pump brands, there are several options available in the market. Here is an overview of some popular and reputable fuel pump brands:

Bosch

Bosch is a well-known and trusted brand in the automotive industry. They have been in the business for over a hundred years and are known for producing different types of premium fuel pumps for both light and heavy-duty vehicles. Bosch fuel pumps are designed to meet OE (Original Equipment) specifications and offer features such as high tolerances for longer lifespans, pulsation-free pumping, and quiet operation.

Walbro and TI Automotive

Walbro, under the award-winning manufacturer TI Automotive, has been in the market for over six decades. Their fuel pumps are known for superior handling of hot fuel and dual-channel motor technology. TI Automotive's products are featured in high-performance vehicles like Bugatti and Dodge. Walbro fuel pumps are made in the United States and offer enhanced pump efficiency with low power draw.

Carter Fuel Systems

Carter Fuel Systems has been in the automotive industry for over a century as well. They offer a wide range of products for domestic, marine, import, performance, and diesel applications. Carter fuel pumps are designed with modern innovations like CleanScreenTM filtration and high-efficiency turbine technology. Their pumps feature non-pulsating pump designs and premium OE specifications for better performance and durability.

Airtex

Airtex is a major fuel pump manufacturer with branches in Mexico, Spain, Germany, and China. They supply both mechanical and electrical fuel pumps for OE and aftermarket industries. Airtex fuel pumps adhere to OE specifications and are thoroughly tested. They also feature precision-ground bearing assemblies and sturdy housings for smooth operation and longevity.

Delphi Technologies

Delphi Technologies, headquartered in Dublin, Ireland, has been manufacturing both OE and aftermarket fuel pumps since 1995. They are known for producing reliable products and continue to improve their fuel pumps through research and innovative technologies. Delphi fuel pumps are engineered to OE standards and made from premium materials to resist corrosion and offer longer service life.

Denso

Denso is a large Japanese auto parts manufacturer that has been supplying the global market for over 70 years. Their fuel pumps feature uniquely designed impellers for efficient and smooth fuel flow, accurate pressure metering, and in-built coils that reduce radio interference. Denso fuel pumps are available for both OEM and non-OEM applications and fit a wide range of vehicle makes.

ACDelco

ACDelco is a US brand primarily manufacturing auto parts for General Motors. They offer fuel pumps built to exacting standards, meeting GM original equipment specifications for fit and function. ACDelco fuel pumps are designed for reliable performance in a wide range of conditions and feature premium materials for enhanced durability.

Pierburg

Pierburg, a Spanish company founded in 1957, has a strong presence in the European market and supplies fuel pumps worldwide. Their fuel pumps are made to strict OE standards and feature quality materials that ensure longevity and accurate pressure metering. Pierburg fuel pumps are known for optimum pumping, even when hot, and low noise levels during operation.

Spectra Premium

Spectra Premium, headquartered in Quebec, Canada, is a top fuel pump manufacturer with factories, warehouses, and facilities in Canada, the USA, and Mexico. Their fuel pumps are quality-controlled, tested, and designed to conform to OE standards in form, function, and fit. Some of their pumps feature carbon commutators for reduced heat and longer life.

Mitsubishi

Mitsubishi, known primarily as a vehicle manufacturer, also produces high-quality fuel pumps. Their fuel pumps are designed to withstand different fuels, run quietly, and meet or exceed OE specifications. Mitsubishi fuel pumps offer excellent fuel flow and pressures and are available globally.

Motorcraft

Motorcraft, a division of Ford Motors, produces fuel pumps specifically for Ford and related brands such as Lincoln and Mercury. Their fuel pumps feature efficient turbines, precision-balanced armatures for reduced noise, and accurate fuel gauge readings. Motorcraft fuel pumps are fully flow-tested to ensure quality and are available at Ford outlets and select auto parts stores worldwide.

Magneti Marelli

Magneti Marelli, an Italian auto parts company founded in 1919, researches, designs, and manufactures fuel pumps for both original equipment and replacement requirements. Their fuel pumps offer efficient electrical connections, ultra-balanced armatures for low noise, and improved filtration for longer pump lifespan. Magneti Marelli supplies car makers in Europe, Asia, and the Americas, and their products are known for their quality and innovative designs.

Vemo

Vemo, a German company founded in 1998, has quickly become a recognized manufacturer of automotive components, supplying to over 125 countries worldwide. Their fuel pumps are made with quality materials, meet exacting OE specifications, and offer low noise and reduced radio interference. Vemo is committed to delivering quality products and offers a wide range of automotive components.

Valeo

Valeo, a French company founded in 1923, is one of the oldest in the industry. They produce a variety of auto parts, including fuel pumps, that are known for their quality and durability. Valeo fuel pumps can withstand damage and corrosion due to premium materials, offer higher tolerances for different conditions, and have innovative designs that ensure optimal performance and fuel flow rates.

Meyle

Meyle, a German company established in 1958, has a global presence in over 120 countries. Their fuel pumps undergo rigorous testing and are made with premium raw materials to ensure reliability and durability. Meyle fuel pumps can withstand different fuel blends, provide accurate metering, and improve flow rates and pressures.

Retech

Retech, a division of the Universal Manufacturing Company based in the USA, has been a leader in supplying aftermarket and remanufactured car parts since 1946. Their fuel pumps meet OE standards, offer reliable performance with quality materials, and feature non-pulsating fuel flow for smooth rides and low noise output.

Mapco

Mapco, a German company founded in 1977, initially specialized in brake parts but has since expanded its product line to include fuel pumps. Their fuel pumps meet or exceed OE requirements and are made with durable materials that resist corrosion. Mapco fuel pumps provide optimal fuel flow rates and non-pulsating operation for smooth drivability.

Swag

Swag, a German brand under the Bilstein group, manufactures a wide range of car parts, including OE and aftermarket fuel pumps. Their fuel pumps are made with quality materials,

Frequently asked questions