What are the Signs of a Weak Fuel Pump? (2023)

When your fuel pump malfunctions, it is bound to affect the performance of your automobile. On average, fuel pumps start to fail after the 10,000-mile mark, despite the anticipated 20,000-mile mark lifespan. And even if it does not fail, it may affect the fuel uptake leading to a whole other host of car problems.

So what are the signs of a bad fuel pump? Depending on how badly damaged the fuel pump is, the symptoms can range from inability to start up to overheating, potentially leading to engine damage. The issues at hand are primarily determined by the type of pump, among other factors.

How Does a Car Act When the Fuel Pump is Going Out?

Newer car models usually have an electric fuel pump that supplies fuel to the engine at a high pressure using an electromagnetic motor. Unlike mechanical pumps, the symptoms of a failing electric pump are harder to detect. Their internal composition is more complex, making it harder to pinpoint the precise cause of the failure.

Symptoms of a failing electric pump

  1. Bad fuel pump sound

A properly functioning fuel pump usually hums quietly, unlike a spoilt pump that will produce a whining or howling sound. This sound will be coming from the fuel tank location as this is where the fuel pump is located.

  1. Starting the car is difficult.

While a bad pump may still be able to pump fuel, it may not be in a position to pump enough fuel to get the car started due to low pressure. This, in turn, causes the car engine to have difficulty starting the car due to the reduced influx of fuel for combustion.

  1. Sputtering engine

If the fuel pump is not supplying a constant fuel stream, the engine may stutter due to the pulsing fuel supply. This happens when you drive at high speed as the engine requires a larger fuel supply to accelerate the vehicle.

  1. Car failure due to overheating

Regular stalling when the car is overheating is a sign of a bad fuel pump. This is because the engine is not getting enough fuel and, as such, is straining to power the car, which in turn causes it to overheat.

  1. Power loss when under stress.

When accelerating up a hill or carrying heavy cargo, loss of power is a sign of a failing fuel pump. This is because a car needs more fuel when operating under stress. And the lack of consistent furl supply reduces the engine’s power.

  1. Car surging

Due to a malfunctioning pump, poor fuel resistance may cause the car to surge due to fuel supply interruptions. The vehicle will feel like you have stepped on the gas pedal even when you haven’t. It tends to happen randomly when you are cruising.

  1. Poor gas mileage

Due to the inconsistent fuel supply, your gas mileage will be higher than usual. Higher gas usage when all other factors such as route and speed remain constant is a sign of a bad fuel pump. This is due to increased fuel being pumped into the engine.

  1. The car does not start.

If your fuel pump is damaged beyond repair, then the car will fail to start up. This is because there is no fuel to combust in the engine needed to power the vehicle. The engine will jump when you start the car, but the car will not turn on.

Symptoms of a Weak or Failing Mechanical Fuel Pump

Mechanical fuel pumps are powered by the energy produced when the engine is running. They tend to have a simple design as compared to an electric fuel pump. They feature a diagram located over the fuel tank that moderates the supply of fuel to the engine. Fortunately, mechanical fuel pump issues are easier to diagnose.

That said, weak mechanical fuel pump symptoms are pretty similar to those of an electric fuel pump. The critical difference is the design of the pump and the simple repair options.

Signs of a Bad Fuel Pump Relay

The fuel pump relay essentially controls the power of the fuel pump. It is found in all vehicles that have an internal combustion engine. Its power is controlled by the ignition or powertrain control module. A failing fuel pump relay is responsible for several of the weak fuel pump symptoms. These include;

  1. Engine fails to start due to lack of power supply to the fuel pump.
  2. The engine stalls when the fuel pump relays power cuts to the fuel pump, leading to fuel restriction to the car engine.
  3. The car loses power while on the road due to inconsistent fuel supply to the engine.

What would cause a new fuel pump to go bad?

The three leading causes of fuel pump failure are fuel contamination, clogged filters, and electrical issues. The use of adulterated fuel can corrode the fuel pump causing it to fail. It may also clog the pump causing it to malfunction. Additionally, debris in the contaminated fuel may block fuel filters which will affect the flow of fuel.

Rusted connectors, loose wires, faulty or melted wiring will cause your fuel pump to stop working. In most cases, this is the leading cause of a failing fuel pump that is relatively new. To check if the electrical connections are faulty, use a voltmeter to check for continuity.

Will a Car Start with a Bad Fuel Pump?

It depends on how damaged the fuel pump is and the part of the fuel pump that is damaged.

How to start a car with a bad fuel pump

Unless your car is not starting up, you can still use your car even with a failing fuel pump. And considering the fact you have to drive it to a car shop to get it repaired, you have to drive it one more time before you get the pump replaced.

The key is to ensure you do not damage other parts of your car while driving with a spoilt fuel pump. That said, after assessing the fuel pump damage, it is advisable to get the vehicle towed or fixed on-site if driving the car will lead to permanent damage to other car parts.

Getting the car started with a bad fuel pump;

  • Use a fuel pressure gauge to determine the amount of fuel going into your car engine. Attach the fuel gauge to your engine directly to circumvent the bad fuel pump and enable your car to start and run.
  • Next, you need to apply external pressure to jump-start the car. This entails manually pushing the car to get it started. This will give the vehicle enough force to get the engine revved up, thus initiating fuel uptake despite the weak fuel pump.
  • Lastly, you can ensure your car engine is sufficiently heated to aid in the fuel uptake. A cold engine will cause the fuel pump to reset, which will impede its ability to pump fuel.

Note: try to limit driving your car with a bad pump unless you are making a trip to your mechanic to get it fixed. Driving with a pad pump can lead to engine damage, power loss, and other issues, which are costlier to fix than just getting a new fuel pump installed.

Check this too: How Often Should You Change Spark Plugs?

Temporary fuel pump fixes that might work

If your car is still running, you may be able to get a few more miles out of your fuel pump if you patch it up. Granted, it will not last for long, but it should be able to serve you until you can get it replaced. Here are some easy short-term solutions for a malfunctioning fuel pump;

  • Fix the fuel tank with gas as a low fuel level exerts the fuel pump. The full tank will make it easier for the pump to work.
  • Replace the strainer or filter in the fuel tank. Also, ensure you remove all the debris in the fuel tank to avoid clogging the filter again.

Note: ensure you put the car on the emergency brake, turn off the engine, and park the vehicle on a flat surface before attempting these temporary fixes. Additionally, check if your car has enough fuel in the fuel tank.

After you are done fixing the pump, you will need to test if the fuel pump is working. This entails turning on the car which will lead to fuel consumption. Lastly, look at the fuel filter and fuel pressure regulator to see if they are still working correctly.

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