Facing engine sputtering or starting troubles?
These issues are symptoms of a bad fuel pump.
What’s more?
Driving with a faulty fuel pump can lead to poor fuel efficiency, unexpected breakdowns, and costly engine repair.
Wondering how you can identify a dying fuel pump early?
Read on to learn about the bad fuel pump symptoms, how much it’ll cost to replace the part, and more.
This Article Contains:
- 9 Faulty Fuel Pump Symptoms to Watch For
- How to Test and Replace a Faulty Fuel Pump?
- How Much Does It Cost to Replace a Fuel Pump?
- How to Keep Your Fuel Pump in Good Shape
- 3 FAQs about Fuel Pumps
9 Faulty Fuel Pump Symptoms to Watch For
A weak fuel pump can result from many common causes, including regular wear, electrical problems, or rough driving. However, catching the following bad fuel pump symptoms will help you zero in on the problem quickly:
1. Engine Sputtering, Surging, or Jerking
A fuel pump malfunction, bad fuel pump relay, or clogged fuel filter can disrupt fuel flow.
This can lead to:
- Excess fuel delivery that results in sudden surges
- Reduced fuel supply that causes the engine to jerk or hesitate
- Sputtering engine due to power fluctuations
2. Engine Power Loss
Fuel pump issues can cause power loss, especially when going up steep inclines or carrying a heavy load. It can also occur when you drive at high speed. Power loss happens because a weakened fuel pump motor can’t meet the energy demand.
3. Engine Misfire and a Glowing Check Engine Light
Because a weak fuel pump can’t deliver sufficient fuel to the engine, the air-fuel mixture will be lean (too much air). This can cause engine misfires due to incomplete combustion.
The check engine light (CEL) will likely pop on, and a scan tool reading will show misfires on multiple cylinders. As there’s only one fuel pump for all the cylinders, the cylinders will be randomly affected. On certain vehicles, the fuel pump itself can trigger the CEL.
Note: Sometimes, faulty spark plugs or spark plug wires can cause the vehicle’s engine to misfire. Also, remember that a lit CEL is a common sign for many other issues.
4. Difficulty Starting or a Dead Engine
A malfunctioning fuel pump or fuel pump relay can mean your vehicle takes longer to build the fuel pressure needed to inject fuel into the engine, leading to starting troubles. You might even have a completely dead engine that won’t start.
5. Engine Stalling
If your vehicle’s fuel pump is failing, it’ll have trouble supplying enough fuel and fuel pressure to keep your engine running. Engine stalling requires a significantly low fuel pressure, so this usually happens when your fuel pump is close to total failure. It’ll first happen occasionally, then increase in frequency.
6. Whining Noise
A fuel filter prevents debris and contaminants from entering the fuel pump. However, a clogged fuel filter restricts fuel flow from the fuel tank to the engine, increasing the stress on the pump. This fuel pump malfunction makes it difficult to maintain the required pressure and will generate a whining noise. Over time, the additional stress can damage the pump as well.
Now, this differs from the momentary whirring noise in some cars, which is your vehicle’s fuel pump priming when you turn on the ignition. If the whirring becomes louder, turns into a whine, or suddenly disappears, you have a fuel pump problem.
Note: A fuel pump issue, vacuum leak in the engine’s intake manifold, or timing belt problem can also cause the whining noise.
7. Overheating Engine
The engine’s cooling system is designed to maintain an optimal engine temperature. However, when your fuel pump goes bad, it can’t supply adequate fuel, leading to a lean air-fuel ratio. The imbalance forces the engine to work harder, generating more heat than can be cooled.
8. Poor Fuel Efficiency
A malfunctioning fuel pump leads to uneven fuel flow to the engine’s cylinders. Excess fuel flow causes reduced fuel efficiency, meaning your gas mileage takes a hit. Fuel injection issues or problems with the fuel rail pressure sensors can make this worse.
Note: Besides fuel pump failure, a loose or damaged gas cap can allow gasoline vapors to escape from the gas tank, causing fuel evaporation and reduced fuel efficiency.
9. Failed Emissions Test
Incomplete combustion can result in higher levels of unburned hydrocarbons and carbon monoxide in the exhaust. These increased pollutants can lead to a failed emissions test.
When faced with a fuel pump issue, repair is rarely an option. The standard procedure is replacement. Let’s find out how.
How to Test and Replace a Faulty Fuel Pump?
Swapping out the fuel pump can be tricky. You should also test the fuel pump first to confirm it’s the problem.
Note: It’s best to let a mechanic handle the checks or repairs since accessing the fuel pump can be difficult and may require specialized tools. Not to mention that dealing with fuel fumes without the right gear is a safety hazard.
A. Test the Fuel Pump
Here’s what a mechanic might do to confirm a weak fuel pump:
- Listen for sounds: Listen for a low hum when turning on the ignition. No noise or loud whining from the gas tank can indicate a failing fuel pump.
- Visually inspect the fuel system: Inspect the fuel filter for clogs that impede fuel flow and the fuel tank for leaks. If they detect clogs or leaks, a mechanic will resolve them before continuing with other tests.
- Test the fuel pump relay: Try to start the engine after switching the fuel pump relay in the fuse box with another relay. If the car starts, the original relay may be faulty.
- Fuel pressure test: Connect a fuel pressure gauge to the pump rail and take a pressure reading. A low fuel pressure reading compared to the manufacturer’s requirement indicates a bad fuel pump.
B. Replace the Fuel Pump
Here’s how mechanics typically do a fuel pump replacement:
- Relieve the fuel system pressure: Run the engine and pull the fuel pump relay. Keep the engine running until it consumes any remaining fuel in the system and stalls. Disconnect the battery, as a spark near an open fuel source would be bad.
- Locate the fuel pump: In modern vehicles, it’s usually inside the fuel tank, though some are externally mounted. The mechanic may have to remove the fuel tank from the car to access it.
- Disconnect and extract: Disconnect the electrical connectors and the fuel line from the fuel pump. Extract the old fuel pump assembly.
- Replace and reconnect: Per manufacturer guidelines, replace the bad fuel pump with a new one. Then, reconnect the electrical connectors and fuel line to the new fuel pump.
- Finish up: Reassemble any removed components, reconnect the battery, and prep the fuel system by turning on the ignition. Look out for leaks or strange noises.
- Test and clear codes: Start the engine, monitor fuel pressure, and assess engine performance. Use an OBD-II scanner to clear any stored trouble codes.
Next, we’ll explore the replacement cost estimate.
How Much Does It Cost to Replace a Fuel Pump?
Plan to spend around $1,100 to $1,300 to replace a bad fuel pump. A new fuel pump costs about $500 to $600. However, labor can cost $600 to $700 since accessing the fuel pump isn’t always easy.
Bear in mind that you might need extra work — like replacing the fuel filter or fixing your fuel tank leaks — which hikes up overall costs.
Wondering how to keep your fuel pump in good condition?
Read on to find out.
How to Keep Your Fuel Pump in Good Shape
Here are some tips to help you maintain your fuel pump:
- Use high-quality fuel from reputable sources.
- Follow your car’s maintenance schedule, including timely checks and replacements for the fuel filter, fuel injectors, and fuel rail.
- Add fuel system cleaning additives every 3,000 miles to prevent contamination.
- Address any fuel leaks or other signs of a bad fuel pump promptly.
- Drive gently to reduce the strain on the fuel pump.
- Keep your gas tank at least 1/4 full. Gasoline cools down in-tank fuel pumps, and if the tank is empty, the fuel pump tends to overheat — shortening its lifespan. Low fuel levels also mean extra work for the pump to deliver fuel.
Still have doubts about fuel pumps?
Let’s resolve them.
3 FAQs about Fuel Pumps
Here are answers to some queries on fuel pumps:
1. How Does a Fuel Pump Work?
The fuel pump draws gasoline from the tank through the fuel filter into the fuel line and delivers it to the engine.
Older cars used mechanical fuel pumps driven by the spinning camshaft. These mechanical fuel pumps push fuel to the carburetor and spray it into the cylinders. In these systems, a mechanical fuel pressure regulator controls the fuel pressure delivered to the engine.
In modern vehicles equipped with an electronic fuel injection system, an electric fuel pump motor handles fuel delivery. The electric fuel pump is typically located inside the fuel tank and is more suited to systems needing a higher fuel pressure. It’s also considered safer because it’s positioned farther away from the engine, and the surrounding gasoline acts as a coolant.
2. How Long Does a Fuel Pump Last?
On average, your vehicle’s fuel pump can last anywhere from 100,000 to 200,000 miles or more. Longevity depends on factors like vehicle usage patterns and car maintenance practices.
3. Is It Safe to Drive with a Failing Fuel Pump?
Neglecting a fuel pump problem endangers your safety and can lead to costly auto repair. If you suspect a dying fuel pump, get a qualified mechanic to check and replace it.
Resolve Faulty Fuel Issues with AutoNation Mobile Service
Fuel pump failure can lead to various engine performance issues, including loss of power, stalling, or overheating. Recognizing these signs is essential to prevent expensive repairs and maintain road safety.
Worried about getting your car to a mechanic?
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