What is Fuel Pump?

The purpose of the fuel pump is to transfer fuel from the fuel tank into the injectors where they spray into the engine to mix with air and spark to create combustion.

Without a properly functioning fuel pump, the engine may experience issues such as hesitation, misfires, or stalling.

Where Is the Fuel Pump Located?

In many vehicles, especially modern ones, the fuel pump is typically located inside the fuel tank. This placement helps to submerge the pump in fuel, which helps to cool it and reduce the risk of vapor lock. [1]

Additionally, locating the fuel pump inside the tank also helps to reduce noise and provides a more consistent fuel supply to the engine.

Bad Fuel Pump Symptoms

A malfunctioning Fuel Pump can manifest in various symptoms, indicating potential issues with the vehicle’s performance:

  1. No Start Condition: When the fuel is faulty, it can fail to provide the necessary fuel pressure to start the engine, resulting in a crank but no start condition. It’s a common symptom of a bad fuel pump that indicates the engine is not receiving fuel for combustion despite cranking.
  2. Longer Crank before Start: A fuel pump that is beginning to fail may still provide some fuel pressure, but not enough to start the engine immediately. This can lead to longer cranking times before the engine finally starts. It’s a sign that the fuel pump is struggling to maintain adequate pressure in the fuel system.
  3. Power Loss: A weak fuel pump can’t deliver enough fuel to match the increased airflow demanded by the engine, leading to a lean fuel-air mixture. This lean condition can cause a loss of power since the engine isn’t receiving the necessary amount of fuel for efficient combustion.
  4. Check Engine Light: The check engine light may illuminate due to various issues related to a weak fuel pump, such as lean air-fuel mixture, engine misfires, or low fuel pressure. These issues can trigger specific OBD-II diagnostic trouble codes (DTCs) related to the faulty fuel pump, which we will cover in this blog.
  5. Engine stalling: Intermittent engine stalling may occur as a result of insufficient fuel being pressurized into the engine due to a weak fuel pump. This can lead to the engine stalling in various situations, such as during idling, deceleration, or acceleration.

Common Fuel Pump fault codes

Here is a list of codes that are associated with the bad Fuel Pump to look for if your check engine light has turned on

What Causes the Malfunction of Fuel Pump ?

Causes of a Faulty Fuel Pump

  1. Electrical Wire Issues: Poor connections across electrical connectors, broken wiring, blown fuses, faulty relay loss of ground, or issues with previously repaired wires can disrupt the connection with the TPS.
  2. Contaminated Fuel: The presence of dirt, debris, water, or other contaminants in the fuel can cause damage to the fuel pump, leading to clogs or mechanical failure.
  3. Excessive Wear: Over time, the internal components of the fuel pump can wear out due to normal use, leading to decreased efficiency and eventual failure.
  4. Fuel Filter Clogs: A clogged fuel filter can restrict fuel flow to the pump, causing it to work harder and eventually fail.
  5. Fuel Level: Running the fuel tank consistently low on fuel can cause the fuel pump to overheat and fail prematurely, as the fuel acts as a coolant for the pump.
  6. Water Ingress: Exposure to water, particularly from driving through deep puddles or heavy rain, can cause water to enter the TPS sensor housing, leading to malfunction.
  7. Exposure to Road Salt: Vehicles driven in areas where road salt is used for de-icing purposes are prone to corrosion, which can affect the TPS’s performance over time.

How To Test Fuel Pump?

Testing the Fuel Pump can be done using following method:

  1. Check the fuel pressure: Testing a fuel pump begins with checking the fuel pressure at the fuel rail. The fuel rail is a metal pipe that connects the injectors to the fuel pump.
    • Locate Fuel Rail and Test Port: Find the fuel rail in your vehicle’s engine bay. This metal pipe connects the fuel injectors to the fuel pump. Look for the test port on the fuel rail; it’s a small valve-like fitting where you’ll attach the fuel pressure gauge.
    • Prepare Fuel Pressure Gauge: Ensure you have a fuel pressure gauge with the necessary adapters to fit the test port. You may need to refer to your vehicle’s manual or consult an automotive store to ensure you have the correct equipment.
    • Relieve Fuel Pressure: Before attaching the gauge, relieve any built-up pressure in the fuel system to prevent fuel spray. This can typically be done by removing the fuel pump fuse or relay and then cranking the engine a few times.
    • Attach Fuel Pressure Gauge: Once the pressure is relieved, attach the fuel pressure gauge to the test port on the fuel rail. Ensure it’s securely connected to prevent leaks during testing.
    • Turn Ignition On: Turn the ignition key to the “ON” position without starting the engine. This activates the fuel pump and allows you to measure the pressure in the fuel system.
    • Read Pressure: Look at the reading on the fuel pressure gauge. It should fall within the specified range for your vehicle, which can vary depending on the make and model.

Other Issues That Exhibit Similar Symptoms as a Bad Fuel Pump

When a car exhibits the symptoms mentioned above, and the Fuel Pump has been checked and found to be in working order but the issue persists, it’s essential to inspect the other components of the fuel delivering system.

  1. Faulty Fuel Pump Relay: The fuel pump relay controls the electrical power supply to the fuel pump. If it malfunctions or fails, it can disrupt the fuel pump’s operation, leading to similar symptoms as a bad fuel pump.
  2. Clogged Fuel Filter: A clogged fuel filter can obstruct the flow of fuel to the engine, resulting in reduced fuel pressure and poor engine performance. Symptoms may overlap with those of a failing fuel pump, making it important to check and replace the fuel filter if necessary.
  3. Faulty Fuel Pressure Regulator: The fuel pressure regulator maintains a consistent fuel pressure within the fuel system. If it fails, it can lead to either insufficient or excessive fuel pressure, causing issues such as engine stalling, hesitation, or rough idling. Inspect the fuel pressure regulator for any signs of malfunction and replace if needed.

Related Video


1. Fuel Pump Location : Where is the fuel Pump Located?

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