How to know when your fuel pump is bad?

How to know when your fuel pump is bad?

A fuel pump is normally installed in the fuel tank in brand new vehicles. Older vehicles usually have their fuel pumps attached between the tank and the engine or to the engine. If you find vehicles with the pump attached on the frame rail or in the tank, then most likely, the pump is electric and is being powered by the vehicle battery. For steady engine performance and extended lifespan, it is essential for cars to have clean fuel. There are tiny openings in the fuel injectors which normally clog easily so filters are used to prevent this.

One of the most essential components in a car’s fuel delivery system is a fuel pump. If it is functioning properly, fuel delivery system operates normally. However, if it fails, the vehicle’s engine will stop to run. But, the failure and the trouble it causes to the vehicle can be prevented if the early warning signs are identified. Below are some common causes of fuel pump troubles and how to know when your fuel pump is bad.

Causes of failure

There are various causes of fuel pump failure such as:

Broken wiring

Faulty or broken wiring in the car’s fuel system interferes with the current flow from the relay to the fuel pump. Even the loose, corroded, burnt or melted connectors/wires, and poor electrical grounding can interfere with the voltage or current flow from the relay to the pump, therefore, interfering with its main function which is, to pump fuel to the engine.

Fuel tank problems

Presence of debris/dust, dirty fuel in tank or rust can lead to its malfunctioning. During humid and cool weather, when the fuel tanks are low, they get moist and this leads to the oxidation of the fuel tanks and they form rust. As they are located inside the tank, the rust is ingested into the pump, leading to its failure.

Clogged fuel filter

Presence of contaminants in the fuel tank or usage of dirty fuel can clog the filters or pickup strainer present in the fuel lines. This leads to low pressure and a lower peak flow of fuel and this further weakens its functioning. Clogged filters are usually associated with spoiled fuel line splits/connectors or fractured hoses kinked fuel lines that normally lead to leakage of fuel. These leaks or cracks on the fuel lines can sometimes create vacuum leaks, which interfere with the air-fuel ratio, as a result, make the engine run lean.

Driving on low fuel level

The pumps durability depends on the cooling and the lubrication that the fuel provides. Running your car on a low gas tank time and again, may heat up your fuel tank much faster, eventually overheating your fuel pump. Thus, due to poor or lack of lubrication, it dries up and gets damaged.

How to know when your fuel pump is bad

Fuel pumps normally show many early warning signs, which when recognized on time, will prevent complete damage. Some warning signs are clearly evident if the pump is thoroughly checked – fuel leaks, broken hoses, discolored electrical terminals, bubbled or burnt plastic at the fuse, etc.

There are some other warning signs that are shown by the car itself

such as:

Strange whining sounds

One of the clear as well as the early signs of a fuel pump that is failing is the presence of a high pitched screeching noise, when the car engine is first engaged. But, the noise will disappear slowly after some time. Also, the noise is not the same for every motor vehicle. It normally varies depending on the vehicle type. Inspecting the pump as soon as the strange sounds are developed will help in preventing it from further damage.

Engine misfires

A fuel pump that is failing may cause the engine to misfire and this in turn will cause the vehicle to jerk time and again. Engine misfires may occur quite frequently, most probably three to four times, and afterward the car may run smoothly for several miles. Such signs show that the fuel pump is wearing out, since it cannot maintain a steady fuel pressure.

Issues with starting and accelerating

A dead or failing fuel pump may also stop the car engine from starting and accelerating. If you are certain that the battery and the starter of your car are good, and still experiencing problems with the starting, then that is a sign of faulty relay. As already mentioned above, a defective wiring harness can lead to a poor power supply to the pump, thus, leading to starting troubles and sluggish acceleration.

Extended cranking time of the engine

For the fuel tank components to be cooled down, a maximum amount of fuel that is sent to the car engine will be sent back to the fuel tank. The fuel returning process is aided by an anti-drain back valve in the outlet. When the pump stops working, the valve is closed and this prevents the fuel from going back into the tank. You can identify this condition by the extended cranking time while the vehicle is being started.

Engine loses power

This sign of a car engine losing power can be seen when the car is going at high speeds, particularly when climbing higher ground. If you are certain that your fuel filter is functioning properly, it is safe to assume that the pump is failing.

Those are some of the ways to how to know when your fuel pump is bad. If you identify the above issues in your car’s fuel delivery system, it is advisable to get your car checked by a professional mechanic, who will further make a diagnosis of the problems by conducting fuel volume and pressure tests (using the fuel pressure gauge), and electrical checks (using digital volt and ohm meter). It is only after performing these tests, should you make a decision as to fix or replace the fuel pump.

Timely replacement or repairs will help you to solve the problems quickly. But, while replacing your fuel pump it is always advisable to go for the best quality accessories, supplied by reputed auto dealers, to ensure that you are replacing better performing and durable products.

7 Comments

  1. 12.07.2016 at 17:41

    I have noticed some sluggish acceleration and every now and then my car won't start right away. It is also worth mentioning that I have replaced the starter, battery, and fuel pump. I really shouldn't be having these problems. Could it be that I just need to change my fuel filter, or should I just start with the power relay?

    • Cole
      26.08.2016 at 18:37

      maybe the fuel pump wires. thats what I have to do because I was having the same issue.

    • Oscar
      13.09.2016 at 18:14

      Replace your fuel filter and maker sure that a complete tune up has been done recently

  2. Elyse
    16.08.2016 at 06:39

    I have a high screeching noise from the under my hood at high speeds only. And when it's hot. Could it still be the fuel pump?

  3. Peter
    25.08.2016 at 04:29

    Im new wirh car. I have a mechanical pump is it normal that if car is off the fuel filter will be empty? Im having problem now since i run out of fuel last week. And lastly does bad starter affect the function of my mechanical fuel pump?

  4. Victoria B.
    17.09.2016 at 19:12

    So, i just recently changed my altenator in my 2003 Nissan Altima. It worked fine all day, and then on my way home after coming to a stop, when i got ready to accelerate again, the car had lost power. We waited about 5 mins, and it started back up and i rushed home. I want to go get a diagnostic, but i'm afraid it'll cut off on me again.

  5. F Hengombe
    03.10.2016 at 15:08

    I had the same problem,I guarenty you,not to take out the relay,I replaced the petrol pump and all my problems were solved,the car is running smoothly,with a high engine performance and make that u check your battery power at the same time you replace the petrol pump.

Leave a Comment