5 Reasons Your Car Hesitates When Accelerating

Pressing on the gas pedal and instead of instant power, your engine sputters and leaves you lagging? Don’t assume the worst just yet. Sluggish acceleration is sometimes an easy DIY fix.

Continue reading to learn the common causes for hesitation under acceleration before your mechanic starts unnecessarily replacing parts. Don’t simply ignore the problem as inconsistent and unpredictable acceleration is a bigger danger than you may think.

acceleration hesitation

Top 5 Causes of Hesitation When Accelerating

Below are five of the most common reason your car hesitates to accelerate as expected when you step on the gas pedal.

#1 – Bad Fuel Pump

bad fuel pump

Vehicles are made with fuel pumps built right in the fuel tank or just outside it. The job of the fuel pump is to deliver fuel to the engine when it is needed for combustion.

The fuel pump must be precise in the amount of fuel it delivers. This means it needs to have the right pressure to do this.

But if the fuel pump is worn out, damaged, or faulty, then an incorrect amount of fuel will go to the engine. This will cause engine hesitation, especially when you’re trying to accelerate up an incline.

Alternatively, a faulty fuel pump relay may actually be the root cause which would prevent the fuel pump from turning on.

#2 – Mass Airflow Senor

bad MAF sensor

Each vehicle has a mass airflow sensor (MAF) which can detect the amount of air that is going into the engine. Once it has this information, it is transmitted to the main computer of the vehicle.

From there, it communicates with the fuel injectors to deliver the proper amount of fuel for the ideal air/fuel ratio. But if the mass airflow sensor becomes faulty or worn out, then it won’t detect the proper amount of air and this will cause problems with the internal combustion process. The result can be engine hesitation.

#3 – Bad Fuel Injectors

fuel injector replacement cost

The cylinder of the internal combustion chamber depends on fuel injectors to spray fuel into it. That way, the right amount of fuel can mix with the air in the chamber and then the spark plug can ignite the mixture.

However, if the fuel injectors are faulty, worn out, or simply dirty, then it will fail at injecting the right amount of fuel into the cylinder. As this continues, engine hesitation will gradually become a reoccurring thing.

#4 – Throttle Position Sensor

bad throttle position sensor

The computer of a vehicle depends on the throttle position sensor to tell it the amount of pressure placed on the accelerator and how open the throttle is. Based on this information, the computer will modify the mixture of fuel and air so that the correct amount enters the engine.

A damaged or bad throttle position sensor will cause the wrong information to get sent to the computer. Then the engine won’t be able to handle different actions, like idling or accelerating.

Read Also: Code P0122, Code P2138

#5 – Clogged Fuel Filter

fuel filter replacement interval

The job of a fuel filter is to prevent rust, dirt, and other particles from getting mixed in with the fuel before it enters the internal combustion chamber. Hesitation when accelerating is a common symptom of a clogged fuel filter.

It is important for car owners to change their fuel filters periodically after a certain number of miles driven. If the fuel filter in a car is not changed, then debris particles will eventually build up on the filter and cause it to get clogged.

Once it is clogged, the fuel will have a tough time passing through the filter. This means the engine won’t get the proper amount of fuel and so it will cause the engine to hesitate. The cost to replace your fuel filter is cheap so there’s no reason not to take care of it.

Mark Stevens


  1. Thank for the information. This was very helpful! I knew that it had to do with ineffective air-to-fuel mixture, but you mentioned other items for which to inspect. Will have our local mechanic look into this. Thanks again!

  2. Excellent suggestions. However won’t the on board computer report any defective sensors. Like the fuel pump, Mass flow, Throttle position

  3. This is helpful and especially the comment on the hesitation when going uphill. I hope the 2014 pathfinder I have won’t be too costly to repair

  4. Thanks WE are due for an oil change so of course I will mention the problem to the best mechanic in the world. My guy is the one .Thanks again Cyndi

  5. 2011 camry 366k miles all stock never change anything. Going to change the coil and spark plugs (last done 40k ago) this weekend and if it doesn’t help with lacking of power going uphill issue, fuel filter and fuel pump is next. This article is helpful.

  6. Our Toyota Corolla was driving great all am then all of a sudden it hesitated over and over within 5 minutes going home would that narrow down the 5 reasons to one or 2 reasons?

    1. Good day car hesitate and slip. But engine make loud noise when the gear slip. Gear won’t shift to next and can only move slowly. When I press accelerator rpm will go high and car will just move slowly. If i continue pressing the accelerator, not minding the engine noise, the gear will select and I can drive fast up to only 40kmh. The problem will start all over again if I the the gear in park and I want to run again. 00 camry Toyota 5s fe engine a140e gear

      1. That’s a tough one to diagnose without hearing the sound and where it’s coming from. Can you describe the sound in detail?

        It’d probably be best to bring your car to a nearby mechanic.

    1. Thank you for your useful reply.
      We often drive our car on a near empty gas tank, which may be responsible for the problems.

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