How To Check And Replace A Fuel Sender Unit?

A fuel gauge that shows it’s empty or full all the time even if it isn’t or its needle moves unusually. If you run out of gas even though you hardly used any, then all these situations are all due to one problem, and that’s the possibility of having a faulty fuel sender unit.

It’s a fairly straightforward task to perform. We’ll let you know how to check and replace a fuel sender unit, and with simple tests and inspections, you’ll find the root of the issue.

Tools That You’ll Need

• An owner’s or service manual helps a lot as it’ll tell you where the fuel sender unit is located, plus it’s also useful for any other related information.
• A multimeter to check electrics.
• Some basic tools.
• An OBD-II scanner if you have one.

What’s A Fuel Sender Unit Used For?

A fuel sender unit is used for measuring how much fuel is in the fuel tank, and you can see the fuel level from the fuel gauge on the dashboard. Whenever the fuel gauge reads this fuel level wrong, the most common cause is a faulty fuel sender unit. Like any other car instrument on the dashboard, a fuel sender unit can sometimes get faulty due to various reasons. The solution here is to check the car’s instrument, find out the cause of the fault and replace or fix it.

Using An OBD-II Scanner

If the dashboard shows an illuminated engine light, this indicates that one of your car’s monitored systems has a fault. An OBD-II scanner or a code reader can be used through your car’s OBD port to locate the fault. If there are issues with the fuel level sensor circuit. The most common OBD-II codes regarding the fuel sender unit are;

• P0460 Fuel Level Sensor Circuit Malfunction
• P0461 Fuel Level Sensor Circuit Range/Performance
• P0462 Fuel Level Sensor Circuit Low Input
• P0463 Fuel Level Sensor Circuit High Input
• P0464 Fuel Level Sensor Circuit Intermittent

All of these codes have a possibility of being related to electrical faults, so remember to check the connections and grounds of the circuit, and while you’re at that, check the battery connections as well, just in case, to ensure nothing is wrong with either of the two. Sometimes when you’re fueling your car with the engine running, the sudden change in fuel levels can cause a trouble code in the system. 

How To Check A Fuel Gauge Fuse

If any other gauge besides the fuel gauge is acting up like the oil pressure gauge, the cause could be a fuse problem. With the help of your owner’s manual, you can check where the fuses for the fuel gauge are located. Pull the fuse to see its condition. In case of a blown fuse, replace the fuse and see if it fixed the fuel gauge issue.

Testing A Fuel Gauge

All new cars and trucks have an electronic fuel gauge in them. These fuel gauges have a built-in self-test procedure. You can find this procedure in your car owner’s manual or online. You’ll have to follow certain steps to initiate the self-test procedure. It will test all the displays and instrument panel lights.

It also runs the gauges through their ranges. If in case the fuel gauge doesn’t go from full to empty, this means that the fuel gauge is faulty, and there are no issues with the fuel sender unit.

As the fuel gauge is electronic, you can also check the relay switch that is connected to it. Some car owner manuals also have information about your car’s wiring with related diagrams in them so check if your owner’s manual has some as it helps to know which electronic parts are connected and where are they connected.

Testing A Fuel Gauge With A Multimeter

A weak connection from the fuel sending unit to the signal wire or a poor quality grounding wire can cause incorrect readings. Using your car’s repair manual, you can see the instructions to remove the instrument cluster/fuel gauge from the dashboard.

If the wire looks fine, then check the fuel gauge wire’s voltage with the help of a multimeter that has been set to 20V DC. The fuel gauge should only be receiving 12 volts. If it is not receiving 12 volts due to any reason, check the wires for damage. A loose connection or a corroded wire can be possible issues.

How To Test The Fuel Sender Unit And Its Connections

Now move on to the fuel tank, check for any corrosion or damage on the top of the fuel sender unit. Check that the fuel sender unit is also perfectly situated in the tank. If the unit has a dirty top, take some time out to clean the connectors to help with conductivity. Ensure the ground connection is good as well.

To make sure that proper voltage is being sent to the fuel sender unit set the multimeter to 20 volts. You can also check the voltage regulator to see if it’s working and fit a new voltage regulator if the old one isn’t properly working. A voltage regulator ensures that all electrical components get proper electric current supply. So, after the multimeter is set to 20 volts, turn on the battery and back-probe the input connector on the sending unit, and then check the voltage. Check your car’s service manual to know about the proper voltage supply. If the input voltage is lower than the volts, then check the wiring that goes from the sender unit to the battery as there could be a chance of it being faulty.

When checking the output voltage, check how much voltage is going from the fuel sender unit to the fuel gauge. The voltage should be the same on both wire ends. If there’s a voltage difference then there is either corrosion or a poor wiring connection between the fuel gauge and fuel sender unit.

Replacing A Fuel Sender Unit

• Release the pressure of the fuel tank according to the instructions in your car’s service manual.
• Disconnect the electrical connections and fuel lines from the fuel sender unit.
• Clean the area near the plug and look for any contaminants.
• A non-ferrous tool is important here. Use it to remove the retaining ring.
• Take out the old fuel sender unit with the gasket or O-ring from the tank. Check to see if the new fuel sender unit is compatible with the old one.
• Fit in the new fuel sender unit with the gasket or O-ring. Ensure that the gasket is aligned with the tank and fuel sender unit.
• When replacing a fuel pump sender unit, move on to the fuel line retainers. Install the sender unit by first guiding in the sender unit arm.
• Now, reinstall the retaining ring. If the fuel sender unit uses screws, use the washers that are included to stop leaks and tighten them.
• Snap fuel lines back and reconnect the electrical connectors.
• Look for any leaks.

The Best Fuel Sender Units You Can Get

1.     Spectra Fuel Tank Sending Unit

The Spectra Premium fuel tank sending unit guarantees you excellent performance and perfectly fits in almost all car models.

Features

• Designed to OE (original equipment) fit, form, and functionality.
• Car fuel gauge provides an accurate reading at any fuel level due to Spectra’s precision-tested fuel level sensors.
• Manufactured in high quality material.

Pros

• Excellent fit for almost all cars.
• High-quality material.
•  
• Designed to fit and function perfectly.

Cons

• It may not be compatible with some pickup truck models.