Your fuel pump moves fuel such as gasoline or diesel from the tank to the engine. If it has a problem, most of the time, you’re not going anywhere and need to diagnose why it stopped working. We’ve already looked at what the fuel pump is and does.
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Thankfully, it can only be due to a few common issues that your pump stops working, and we have a fix for each scenario to share with you.
#1 – Your Fuel Pump is Bad
Your fuel pump can be mechanical or electric, but in either case, its job is to move fuel from the tank to the engine. If the pump is bad or stops working, it will stop moving fuel.
Electric pumps have an electric motor that attaches to an internal impeller that converts electricity into motion to pump the fuel. If the impeller or electrical parts like the rotor, brushes, or connector fail, the pump will stop working correctly.
Mechanical pumps have an internal diaphragm that uses mechanical movement to pump the fuel. These types are normally connected directly to the engine to reduce part and movement complexity.
Electrical pumps, on the other hand, can be inside the fuel tank or in line with the fuel hoses.
How to Fix It
If the fuel pump is bad, it may be able to be rebuilt or simply replaced with a new one. The choice may come down to what is available for purchase and the cost of either option.
#2 – The Electrical Connection Is Broken
An electric pump needs electricity to work correctly and make that characteristic hum of pumping fuel. If the electrical connection is broken, the hum doesn’t happen.
How to Fix It
The first step in fixing this common issue is diagnosing why the electricity isn’t flowing to the pump. The electrical connector attached to the pump is an obvious choice as it can become corroded or dirty.
The next thing to review is the wiring leading to the pump to understand if it has been damaged. Damaged wiring can be fixed, and connectors can be replaced as needed.
#3 – The Fuel Pump Fuse is Blown
If the fuel pump doesn’t have power, it is probably easier to check the fuse before crawling under your car to check the wiring and connector.
The fuse can be located near the dash inside the cabin or possibly under the hood in a fuse box. Your owner’s manual should identify where the correct fuses are located.
How to Fix It
This repair is pretty easy, as fuses are meant to come out and be replaced.
Just be sure to replace the fuse with the same amperage rating (they are color-coded to visually help, too) and the same type.
If the fuse immediately blows again or blows soon after you replace it, you will want to check the connector and wiring to determine if it is damaged and causing the fuse to blow.
#4 – The Fuel Pump Relay Has Stopped Working
Electrical relays are used to convert low current into a significantly higher current, which an electric fuel pump requires.
As with all electrical items, they can eventually wear out and fail. Relays are typically sealed and can’t be rebuilt. Here’s an explanation of what the car relay does.
How to Fix It
Relays are another electrical item that needs to be replaced rather than rebuilt.
There are many types of relays with different wiring configurations and amperage ratings, so be sure to buy the exact replacement to match your car.
You can diagnose a problematic car relay by using a jumper wire to make the electrical connection to the fuel pump. If the pump works by using the jumper wire to make the electrical connection, the relay should be replaced.
#5 – The Fuel Pump Filter Is Clogged
You may hear the fuel pump running but still not have a car that runs correctly.
There is a fuel filter between the pump and the engine that removes small particulates that will eventually fill the filter and slow or stop the filter from doing its job.
Beyond the external fuel filter, an electric fuel pump will have a pre-filter (also called a sock) that screens large articulates from entering the fuel pump. This can also become clogged. It is inside the fuel tank, making it harder to check, clean, or replace.
How to Fix It
Most external fuel filters are in line with the fuel hoses under the car. They take basic hand tools to remove and replace, so the easiest fix for a clogged fuel filter is to replace it.
If you determine the pre-filter is your issue, you may need to remove the fuel tank from the car unless there is a fuel pump panel that can be removed to grant easier access.
#6 – Your Fuel Line Connections Are Loose Or Broken
Another potential failing point in the fuel system is the connecting points. The fuel system may use push-lock or threading connectors to join components such as the fuel pump and fuel hose.
These connections can be difficult to secure and they can fail due to corrosion. A failed connection will allow air to enter the fuel system and leak fuel under pressure.
How to Fix It
Once you have determined what connection is the issue, you will need to remedy why it is loose or broken. Broken connectors may need to be replaced, if possible.
Loose connections may be caused by a missed installation or a loose clamp, and need to be corrected.
#7 – The Fuel Pump Seal Or Gasket Is Damaged
Mechanical or electric fuel pumps use a gasket or a seal between the pump and its connecting component, like the fuel tank or engine block.
If that seal, whether a paper gasket or a rubber seal, is damaged, it will allow fuel to leak out or air to enter the system.
Either situation presents a problem and a potential safety issue.
How to Fix It
A mechanical fuel pump may have a paper gasket or a rubber one between the fuel pump housing and the engine block.
These are replaceable with basic tools when the fuel pump is removed.
If you have an in-tank electric fuel pump, you will need to remove the fuel tank from the car to replace the seal on the top of the fuel tank.
If you have a panel on the floor of your car that allows you to remove the fuel pump without removing the fuel tank, you may need to remove the carpet and/or seats to complete the work. The fuel pump will need to be removed and the seal replaced.
#8 – The ECU (Engine Control Unit) Has Failed
The ECU, or Engine Control Unit, controls the fuel pump, among other components, when you drive your car.
If the ECU fails, power won’t be sent to the fuel pump relay to run the pump. The ECU doesn’t fail very often, but if all other issues have been checked out okay, the ECU may be the culprit.
How to Fix It
The ECU is a sealed unit, and not easily repaired. This may be one area that requires a professional to diagnose a failed ECU and repair or replace it, if possible.
The ECU controls many of the car’s vital functions, so tread lightly if you are going to tackle this job by yourself.
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