Todays modern vehicles that use internal combustion engines come equipped with fuel pumps. The fuel pump is responsible for delivering fuel from the tank to the engine at the appropriate pressure required to meet the demand.
When the key is turned on, the fuel pump is activated and pressurised, which can be heard as a quiet whine or hum within vehicles. The fuel pumps fitted on most modern vehicles are electronic, usually mounted inside the fuel tank.
So, obviously any deterioration or breakdown in pump performance will seriously affect your vehicles drivability. Be aware, if you keep your fuel tank around a quarter full, you will shorten the life of your fuel pump as it has to work harder to lift the fuel.
But there are other things to check too, check the fuel filter, especially if you have a diesel, fuel filters have been known to collapse internally even after only a couple of thousand miles. A blocked filter will give the same symptoms of pump failure, but will be the end of your fuel pump eventually too.
Usually a failing pump will give a few early warning signs, and if acted upon, can save you some standing around at the side of the road.
Whining noise from the fuel tank (electronic)
One of the first symptoms of a problem with the fuel pump is a loud whining sound. An old or worn fuel pump may produce a noticeably loud whine or howl when it is running. Most fuel pumps will produce a quiet hum during their normal operation.
Another symptom that is commonly associated with a problematic fuel pump is difficulty starting. Because of how they operate (constantly running whenever the ignition is turned on) over time fuel pumps can eventually wear out and weaken. A weak fuel pump may still pump fuel, however the vehicle may experience difficulty starting as a result of the lack in pressure. A weakened fuel pump can cause the vehicle to take more cranks to start than normal, and in more serious cases may even cause the vehicle to require multiple turns of the key before it will start.
Misfires and a decrease in power, acceleration, and fuel efficiency
Another symptom of a problem with the fuel pump is engine performance issues. As the fuel pump is what supplies the vehicle with the fuel required for combustion to occur, any issues with it can affect the engine’s fuel supply and cause issues. A faulty pump with low pressure will disturb the engine’s air-fuel ratio, which can cause all sorts of performance problems. Aside from hard starting, the vehicle may experience misfires, a loss of power, decrease in fuel efficiency, and finally engine stalling.
The engine will still crank when the key is turned, however it will be unable to start due to the lack of fuel. A no start condition can also be caused by a wide variety of other issues, so having the vehicle properly diagnosed is highly recommended.
Fuel pumps are found on all internal combustion engine vehicles in one form or another. Most fuel pumps are built to last, however as the vehicle enters high mileage, it is not uncommon for fuel pumps to require replacement.
Usually crank powered, these mechanical pumps fail due to wear internally or the diaphragm fails. To check the pumps effectiveness, see if you can feel the pressure once you have removed the fuel line. Also check if your fuel filter is full, if not, the engine is using more than the pump can deliver.