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Will A Bad Fuel Pump Give A Check Engine Light?

Will A Bad Fuel Pump Give A Check Engine Light?

The fuel pump is the part of your car that is usually electric and located just inside of the fuel tank, creating a positive pressure within the fuel lines and pushing the gasoline to the engine so that the car can be powered to run. A fuel pump is in charge of drawing gas out of the tank through a pipe to the carburetor, with the pump being mechanically-worked by the engine or electric.


 

Many engines that are older do not require any fuel pump at all, only needing gravity to transport the fuel from the fuel tank or when it is under high pressure to the fuel injection system, which incorporates the internal combustion engine by the means of an injector. Since older engines do not need a fuel pump, this can help answer the question of “will a bad fuel pump throw a check engine light?” for you. 

 

Almost all modern vehicles that contain internal combustion engines are equipped with a fuel pump. As we know, the fuel pump is in charge of delivering the right amount of fuel from the gas tank to the engine, and must do so with the appropriate pressure required for the specific performance demands. When your key is turned on and the ignition is turned, the fuel pump is turned on as well. 

 

When the key is turned in the ignition, this means the fuel pump is activated and pressurized, which can be audible to either the driver or passenger as a quiet whine or a hum. If you hear louder noises, this answers the question of “will a bad fuel pump throw a check engine light?”

Faulty Fuel Pump Signs

In order to tell if a bad fuel pump will throw a check engine light, you need to know the common signs and symptoms that your fuel pump is failing so you can make sure this is the root cause of your issues. Here are the most common signs and symptoms of a failing fuel pump so that a driver or passenger can easily distinguish the problem before it throws the check engine light.

  • Loud Whining Noise

One of the first symptoms that you will notice with the fuel tank turning bad or being damaged is a loud whining sound that is coming from under your hood. The only good thing about this symptom is it is very noticeable and audible to almost all drivers. An old or worn down fuel pump that has become damaged over time can cause a loud whine or a howl while driving, especially at high speeds. 

 

Most fuel pumps will produce just a quiet hum when they are running smoothly and they are not damaged, but a very loud whining noise indicates a problem with the fuel pump. If you consistently hear loud noises while driving, this can answer the question of “will a bad fuel pump throw a check engine light?”

  • Trouble Starting the Car

Another common symptom that is more times than not associated with a failing fuel pump is difficulty starting the vehicle, with the car having a tough time turning the ignition or revving the engine. Since fuel pumps constantly run whenever the car is turned on, they can eventually wear out and break down over time due to the prolonged use. 

 

A weak fuel pump can still pump fuel through the line and supply gas, but the vehicle could have a more difficult time starting due to the lack of pressure in the fuel system. Due to the lack of pressure in the fuel system and fuel lines, fuel will not be adequately transported, giving you the answer to “will a bad fuel pump throw a check engine light?”

 

If your fuel system and the fuel pump is weakened, this can cause the vehicle to need to crank more times than it would normally take, meaning that the vehicle might require more energy to start, have more difficulty starting, and can throw the check engine light if it is not fixed.

  • Sputtering Engine and Reduced Performance

The third sign that there is an issue with your fuel system and the fuel pump is your engine could be sputtering, especially at high speeds. If you are driving at high speeds, like on a highway and the engine suddenly sputters before it runs normally again, this can show there are serious issues with the fuel pump and the gas system in your vehicle. 

 

If you notice that the engine sputters consistently in your car, the fuel pump is not able to provide a right stream of fuel to the engine at the correct pressure. Without the right pressure in your vehicle, you may have the answer to your question of “will a bad fuel pump throw a check engine light?”

Engine Sputtering Causes

Other causes of engine sputtering can throw off someone who thinks the fuel pump is the initial cause. Other reasons that this might happen with your engine is a blocked fuel injector, incomplete combustion within the engine, the gas gauge is not working properly. The main cause of the malfunctioning engine can be located within several different systems. 

 

In addition to these issues, the engine sputtering might not just be the fuel leak that can throw the check engine light, but other common reasons, like the exhaust manifold leaking. When the exhaust manifold has a leak, it can cause the car to run unevenly, suffer from poor performance, and sputter while using. 

 

Furthermore, a failing catalytic converter can burn off hydrocarbons in the exhaust and cause the engine to sputter, along with a noticeable smell. If you notice a pungent smell in your car along with the engine sputtering, this means that you have the answer to “will a bad fuel pump throw a check engine light?”

  • Engine Stalling

Engine stalling in your vehicle can happen because of various issues, but make sure you know if this stalling only happens at high temperatures that are shown on the thermometer in your car. If this is the case, and the stalling is contributed to the high temperatures, then this can usually be attributed to the fuel pump motor. 

 

If the stalling continues to occur with an increasing temperature, then this is usually because the fuel pump is deteriorating, giving you the answer to “will a bad fuel pump throw a check engine light?”

  • Loss of Power

Another sign of a bad or failing fuel pump is a loss of power when the vehicle is under stress, like driving uphill, draining very fast, or carrying heavy loads in the back of the trunk, or while accelerating quickly like on a highway. The engine shuts down since the damaged parts of the fuel pump can't perform at the necessary level, due to the heightened fuel demands in these specific performance situations.

 

In these instances where your car shuts down, the car will usually feel to the driver as if it cannot provide the intended amount of power. If the fuel pump is the root cause, this means that it can’t regulate the right amount of fuel pressure accurately and provide the right amount of fuel to the engine. Without the proper level of fuel to the engine, you will have the answer to “will a bad fuel pump throw a check engine light?”

  • Car Surging While Driving

Another reason for damage to the fuel pump and the fuel system, and a potential reason for the bad fuel pump to throw the check engine light is irregular resistance located within the fuel pump motor. This can cause the vehicle to surge while driving jerk while accelerating, showing the fuel pump needs to be repaired or replaced. 

 

If you are surging in your vehicle, this feels to the driver like the gas pedal has been used and pressed down. The pedal problem can occur at a random and constant speed, like driving on the highway. If this happens you need to get your fuel pump checked by your local mechanic to determine “will a bad fuel pump throw a check engine light?”

  • Reduced Gas Mileage

If you realize that your fuel economy is poor, your car’s acceleration and performance is suffering, and the car is getting less gas mileage per gallon than it normally does, these are signs of an issue with the fuel pump. If you are filling up your car more than normal, you should check your fuel pump for any issues. 

 

A valve within the fuel pump might not be opening properly or at the right moment, causing more fuel than is required to pour into the engine system unnecessarily. Excess fuel in the engine does not get used or stored for a later date, but just gets wasted in the car. This wasted fuel that is unused will not burn properly, leading you to ask the question of “will a bad fuel pump throw a check engine light?”

  • Car Won’t Start

The final reason that your fuel pump might be damaged and the bad fuel pump is causing the throw the check engine light is that your car can no longer start and turn on, preventing you from driving at all. This is a serious issue that needs immediate fixing, since your car is now no longer operable. If the fuel pump completely fails, then the vehicle cannot start since it does not have enough fuel for the engine to operate.

Testing Your Fuel Pump

 

To determine if a bad fuel pump will throw a check engine light, there are two tests you can use on your car to determine if this part is causing the issues within your vehicle. If you are struggling to accelerate properly in your car, especially when driving at high speeds on the highway, or you notice other signs that your car is not getting enough power, then the problem can most often be attributed to a partially blocked or clogged fuel line, blocked fuel filter, clogged fuel pump, or faulty fuel injector. If your car will not start at all when you are trying to accelerate or drive, there are a few tests you can figure out to run.

  • Electrical Test

One of the main methods that you can use in how to test a fuel pump is using an electrical test. The first step is to check the fuel pump fuse, since more often than not it is not the pump that fails, but the power that supplies it. 

Locate the Fuse Box

Find the location of the fuse box and then find the correct fuse that matches with the fuel pump. Pull out the fuel pump and check for any signs of failure or if the fuse is blown. If the fuse looks good and does not show any damage, then you do not need to replace them. When this is the case, have a helper turn the key while you listen to the fuel pump relay clicking on. If you do need to replace a fuse, make sure that you use one with the right amp rating. 

Check the Voltage

The second step in performing an electrical test is to check the voltage at the pump itself. Just because you are getting some power from the circuit does not mean it is actually traveling directly to the pump, which makes it important to check the voltage in two places. 

Drop Test With Voltmeter

The third step is to perform a drop test with a voltmeter. Make sure the power wire shows that there is full voltage and the grounding wire is positioned correctly. If the electrical test shows no issues, then it is likely that your fuel pump is the issue and needs to be replaced. That is the last step in performing an electrical test when using a method of how to test the fuel pump. 

  • Fuel Pressure Test

Checking the fuel pressure or volume in your car can tell you whether or not enough fuel is going from the tank to the engine. However, this doesn’t necessarily mean exactly that the pump is bad when you are learning how to test the fuel pump. You should check the fuel pressure by using mechanical fuel pressure gauges.  

 

After you check the fuel pressure using the mechanical pressure gauge, you need to perform a static fuel pressure test and connect the gauge as outlined in your repair manual. Then, turn the ignition to the on position and note the reading on the gauge and compare it to specification in your manual. 

Conclusion

You may be asking yourself “will a bad fuel pump throw a check engine light?” If you notice serious signs and symptoms of a faulty fuel pump, then you will have to get this part inspected and fixed before it causes any further issues in your vehicle!