Fuel Pump Replacement: Will Your Tank Drain Out?

The fuel pump is an essential component of a vehicle, transferring fuel from the gas tank to the engine to combust and power the car. A failing fuel pump will cause performance issues, such as sputtering, stalling, and struggling to maintain speed. In some cases, a faulty fuel pump can lead to engine power loss, which could be dangerous. While fuel pumps are designed to be durable, lasting over 100,000 miles on average, they may eventually need to be replaced. When changing the fuel pump, it is necessary to drain the fuel from the tank if there is no access panel in the passenger compartment. This involves removing the fuel supply and return hoses and lowering or removing the tank. So, yes, when changing a fuel pump, all the fuel will be drained from the tank if there is no access panel available.

Warning signs of a failing fuel pump

To answer your initial question, no, not all your fuel will drain out when changing the fuel pump. Now, here are some warning signs of a failing fuel pump:

A fuel pump is designed to last for over 100,000 miles, and some can even go beyond 200,000 miles. However, if you notice any of the following issues, your fuel pump may be failing and need to be replaced.

• Engine sputtering or stalling: If your engine sputters, jerks, or stalls during driving, especially at high speeds or when under stress (such as towing a heavy load or driving uphill), it could be a sign that your fuel pump is failing to deliver a consistent flow of fuel to the engine.
• Noise from the fuel tank: A loud whining or whirring noise coming from your fuel tank could indicate a problem with the fuel pump. Normally, the pump makes a low, barely noticeable hum, so if the pitch increases significantly, it's a cause for concern.
• Poor fuel efficiency: If you find yourself making more frequent trips to the gas station, it could be because your fuel pump is damaged and is pushing too much fuel into the engine, causing you to burn more gas than normal.
• Engine misfire: If your engine misfires, it could be because the fuel pump cannot supply enough fuel, causing one or more cylinders to fire too late or not at all. This can lead to a rough idle or difficulty starting the car.
• Stalling at high temperatures: A faulty fuel pump may struggle to supply enough fuel to the engine when it gets hot, causing the vehicle to stall under high-temperature conditions.
• Vehicle surges: If your vehicle surges forward for no apparent reason, it could be because the fuel pump is delivering too much fuel, causing the car to surge and then slow down.
• Acceleration issues: If your vehicle struggles to accelerate as it should, it could be because the fuel pump is unable to deliver the necessary amount of fuel to meet the engine's demands at higher speeds.
• High engine temperature: An increase in engine temperature, as indicated by the temperature gauge, could be an early warning sign of a failing fuel pump.
• Car not starting: While there could be various reasons for this, a bad fuel pump could be one of them. If the pump is unable to deliver fuel to the engine, the car won't start.

How to test for a faulty fuel pump

The fuel pump is a crucial component of your vehicle, delivering fuel from the tank to the engine. When it goes wrong, it can cause major performance and drivability issues. Luckily, there are several ways to test for a faulty fuel pump.

Check for Fuel-Related Issues

Firstly, you need to verify if the problem is fuel-related. If your engine won't start, or is exhibiting performance issues, there are several things you can try.

• Listen for the fuel pump: Put your ear near the fuel tank and turn the ignition key to the "on" position. A functioning fuel pump should be audible.
• Whack the fuel tank: Get a friend to crank the engine while you hit the fuel tank with a rubber mallet. If the vehicle starts, it's likely that the electric motor inside the pump is faulty.
• Use starter fluid: Warning: this procedure can be dangerous and may damage your engine. Try at your own risk, with safety equipment such as a fire extinguisher and glasses. Attempt to start the vehicle by spraying starter fluid into the throttle body. If the engine starts and runs for a moment, it's likely a fuel-related issue.
• Check for diagnostic trouble codes (DTCs): A faulty pump may set DTCs in your car's computer. Use a scanner or code reader to retrieve this information.
• Check fuel trim with a scan tool: If your engine is running, you can use a scan tool to check the short-term fuel trim (STFT). If the fuel trim is above 10, the engine is running lean and may not be getting enough fuel.
• Check fuel pressure and/or volume: This will tell you whether enough fuel is making it from the tank to the engine. You can use a mechanical fuel pressure gauge to do this.

Advanced Testing

If the above tests indicate a fuel-related issue, you can try some more advanced tests to pinpoint whether the fuel pump is to blame.

• Measure current draw with an oscilloscope: This will show a waveform pattern that can expose internal pump problems. A good pump should produce a pattern of even "humps".
• Use a professional-grade scan tool: Some high-end scan tools allow remote fuel pump testing. You can activate the pump with the push of a button to see if it runs.
• Remove a fuel supply line: Disconnect one of the rubber fuel supply lines in the engine bay and observe whether pressurised fuel comes out.
• Use a multimeter and a wiring diagram: You can probe the wiring at the connection to see if the fuel pump is receiving electric power and the proper signal.
• Disconnect the fuel pressure sensor: Without the pressure sensor, the ECU will assume a worst-case scenario and order the fuel pump to run at full pressure. If your car runs better without the sensor, the pump is likely faulty.
• Test with a fuel pressure gauge: If the pump runs and fuel is reaching the injectors, you can check the fuel pressure or output with a flow meter.

Warning Signs of a Faulty Fuel Pump

Before you begin testing, it's worth noting some of the warning signs of a bad fuel pump.

• The car won't start, or struggles to start.
• The car sputters or dies while driving, especially under stress (e.g. towing or driving uphill).
• The engine surges while driving, caused by too much fuel being sent to the engine.
• You hear whining or whirring coming from the fuel tank. A healthy fuel pump will make a low, barely noticeable hum.
• You notice lower gas mileage.
• The fuel pump makes uncharacteristic noises, such as constant clicking or rhythmic knocking.

The process of replacing a fuel pump

The fuel pump is a crucial component of a vehicle's engine, transferring fuel from the fuel tank to the engine. While fuel pumps are durable, they may need to be replaced if they malfunction or become damaged. Here is a step-by-step guide on how to replace a fuel pump:

Step 1: Prepare for the Replacement

Before beginning the replacement process, it is important to gather all the necessary tools and equipment, including a new fuel pump, fuel filter, and any other vehicle-specific components. It is recommended to reduce the amount of fuel in the tank to minimize the risk of spillage and make the process safer and more accessible. Ensure you are working in a well-ventilated area, preferably outdoors, to prevent the buildup of flammable fuel vapors. Always wear safety gear, such as safety glasses and gloves, to protect yourself from fuel spills.

Step 2: Relieve the Fuel System Pressure

The next step is to relieve the pressure in the fuel system. This can be done by running the engine and pulling the fuel pump relay, causing the engine to stall. Alternatively, with the engine off, you can press the Schrader valve on the pressure line momentarily, releasing a small spray of fuel.

Step 3: Locate and Remove the Fuel Tank

The fuel pump is typically located directly in the fuel tank, so you will need to locate and remove the fuel tank from the vehicle. This process can vary significantly depending on the vehicle model. In some cases, you may need to use a jack to support and lower the fuel tank. In other models, there may be an access port under the rear seat or in the trunk area, providing easier access to the fuel pump.

Step 4: Disconnect the Old Fuel Pump

Before removing the old fuel pump, take note of the fuel line connections and wiring. Carefully disconnect all the connections, turn the large lock nut to free the old pump, and then pull it out.

Step 5: Install the New Fuel Pump

Install the new fuel pump by reversing the removal process. Ensure all connections are secure and correctly attached.

Step 6: Reassemble and Test the Fuel System

Reassemble the fuel system, including the fuel tank, and test the new fuel pump to ensure it is functioning properly. Start the engine and check for any leaks or issues.

By following these steps, you can safely and effectively replace a fuel pump in your vehicle. It is important to take your time and refer to vehicle-specific instructions or consult a professional mechanic if needed.

Fuel pump maintenance tips

The fuel pump is an essential component of a vehicle's engine, drawing fuel from the tank and delivering it to the engine to power the vehicle. Performing regular maintenance on your fuel pump can help extend its lifespan and ensure your vehicle runs smoothly. Here are some tips to keep your fuel pump in good condition:

Keep Your Gas Tank at Least a Quarter Full

Gasoline acts as a coolant for in-tank fuel pumps. Running your vehicle close to empty frequently can cause the fuel pump to overheat and shorten its lifespan. Additionally, low fuel levels require the pump to work harder, increasing the risk of damage. It is recommended to always keep your gas tank at least a quarter full to prevent these issues.

Use High-Quality Fuel

The quality of fuel you use can impact the performance and lifespan of your fuel pump. Poor-quality fuel can leave deposits and debris in the fuel pump, leading to clogs and reduced efficiency. Always use fresh, high-quality fuel from reputable sources, and avoid storing fuel for extended periods without proper storage conditions.

Regularly Change the Fuel Filter

The fuel filter can become clogged with debris, soot, carbon, and metal deposits from other components in the fuel system. This can increase the workload on the fuel pump and affect its performance. It is recommended to change the fuel filter regularly, typically every 10,000 to 25,000 miles, to maintain optimal fuel flow and reduce the risk of damage to the pump.

Perform Regular Fuel System Maintenance

Schedule regular maintenance checks for your fuel system, including the fuel pump, fuel lines, and fuel injectors. This will help identify any potential issues and ensure that all components are in good working condition. Regular maintenance can help extend the life of your fuel pump and prevent unexpected breakdowns.

Monitor Warning Signs

Be aware of any warning signs that may indicate a failing fuel pump. These can include unusual noises under the driver's seat, reduced power or acceleration, surging or stalling of the engine, and decreased fuel efficiency. If you notice any of these symptoms, have your vehicle inspected by a qualified technician to diagnose and address the issue promptly.

The cost of replacing a fuel pump

The cost of labor for fuel pump replacement ranges from about $600 to $700. This is largely dependent on the hourly rate of the mechanic, which can vary from $100 to $150 per hour. The time taken to replace a fuel pump is typically at least two hours.

The cost of parts for fuel pump replacement is about $500 to $600. The price of fuel pumps varies, with some pumps priced at $180, and others at $350.

The total cost of fuel pump replacement is typically between $1,000 and $1,300. However, this can vary depending on the specific circumstances. For instance, the cost of replacing the fuel pump in a Jeep Wrangler was $520, with $275 for the pump and $225 for labor.

It is important to note that fuel pumps are designed to be durable and typically do not need to be replaced until a vehicle has at least 100,000 miles on it. Some fuel pumps have been known to last for over 200,000 miles. Therefore, it is unlikely that most people will need to replace their fuel pumps.

Frequently asked questions