My Car Starts But Wont Accelerate (Reasons and Solution)

Owning a car is a lot easier than maintaining one perpetually. Vehicles come with several responsibilities. While some can be a walkover, others can be very frustrating. For instance, my friend once told me, “My car starts but wont accelerate.”

Such an experience can be highly annoying, especially when you’re set for work in the morning, only to discover that your car has an acceleration problem. If you’re facing this kind of challenge now, this article is for you.

car won't accelerate

In this article, you will learn about the common reasons why a car may start but fail to accelerate and the corresponding solutions to the problem.

Causes of My Car Starts but Wont Accelerate

There are several reasons why your car starts but wont accelerate. Some issues may be relatively easy to fix, while others can be quite challenging like spark plug arcing.

Nevertheless, understanding the causes of the acceleration problem is the initial step out of the problem. Any of these issues may be responsible if your car starts but fails to accelerate.

Blocked air filter

A vehicle’s air filter is designed to trap dirt or other particles from entering the engine, thereby causing negative impacts on sensitive components and sensors. 

Unfortunately, the air filter doesn’t last forever.

In other words, when the component becomes clogged with excessive dirt, you must replace the air filter. Otherwise, the dirt will prevent the free flow of air into the engine, thereby choking the engine and leading to difficulty in acceleration.

Dirty or bad mass air flow sensor

The mass airflow (MAF) sensor is responsible for assessing air entering the engine, thereby sending a signal to the engine control unit to measure how much fuel should be pumped into the engine.

Like the air filter, the mass airflow sensor can become dirty over time as it is consistently used in the vehicle. This usually occurs in cases where you have an open-air filter or in a situation where the air filter has not been cleaned or replaced for a long time.

When the MAF sensor becomes dirty or bad, the component cannot send an accurate airflow signal to the engine control unit. It will most likely measure very little airflow, resulting in a lean air-fuel mixture. This can also affect a vehicle’s acceleration.

Blocked fuel filter

The fuel filter ensures that dirt or other particles do not gain access into the fuel system and damage sensitive parts such as the fuel injectors.

Since the component is meant to trap dirt, it can become clogged over time, preventing optimum fuel flow. When this occurs, the low fuel pressure will eventually result in a lean mixture, leading to vehicle acceleration issues.

Bad fuel pump

The fuel pump is built to deliver the necessary fuel to the engine from the gas tank when required. Unfortunately, electric problems, contaminants from bad gas or dirt, and aging due to constant usage can result in fuel pump failure.

Meanwhile, a bad fuel pump will lead to low fuel pressure and will not be able to convey the required amount of fuel to the engine when needed. Consequently, this will lead to an unexpected defect in a vehicle’s acceleration.

Advanced or retarded timing

Sometimes vehicle malfunctions can result from an incorrect repair of a delicate component such as the camshaft.

If your auto mechanic recently changed your timing belt and suddenly your car won’t pick up speed thereafter, there’s a tendency that the timing is too retarded or too advanced.

You may want to carefully check it out again because an incorrect timing belt or chain installation will eventually cause your car to move slower than expected. Furthermore, a timing belt failure can lead to severe engine problems; hence the issue must be taken seriously.

A timing belt or chain can shift one or two teeth. This usually happens when the chain is stretched or the belt is weak and needs replacement.

Limp mode

Limp mode is another reason you may be experiencing an acceleration issue in your car. This feature is designed to help prevent further damage once a fault is identified as threatening to a car’s engine.

Usually, limp mode switches off non-essential components and reduces a vehicle’s speed once a threat is identified from transmission issues, low fluid levels, and faulty sensors. Electrical system malfunction is also the reason of car acceleration issue. So, if your car is not accelerating as expected, you may want to check if the computer system has triggered limp mode or other problems.

How to Fix Car Acceleration Problems

Fixing car acceleration problems can be very straightforward, especially when you’ve identified the exact cause of the problem. These recommendations are some remedies to acceleration issues, especially if the reasons outlined above are responsible for the fault.

Clean/replace the blocked air filter

If your car stopped accelerating due to a clogged air filter, replace the component or clean it thoroughly. Some air filters are washable, while others are non-washable.

You need the following materials to clean your car’s air filter thoroughly; a soft-bristled brush, vacuum with brush attachment, microfiber towel, protective face mask, soap, and water for washable air filters. For non-washable air filters, you need to clean it with compressed air.

Clean the dirty mass airflow sensor

Cleaning the mass airflow sensor can also help to rectify your car’s acceleration issue if this is the case. To clean the MAF sensor, unplug the component from the car’s electrical system.

Then, remove any brackets and clamps holding it in place. After that, apply the recommended MAF sensor cleaner to clean up the component carefully and allow it to dry before reinstalling.

Replace the clogged fuel filter

If you discover that your car won’t accelerate due to a clogged fuel filter during your diagnosis, the best thing is to replace the component immediately. Replacing a defective fuel filter costs around $70 – $160.

However, you will spend less if you can handle the replacement of the component personally.

Change faulty fuel pump

Since a faulty fuel pump continually hinders your vehicle’s acceleration, replacing the component as soon as possible would be best. The complete replacement cost is estimated at around $900 – $1,100.

However, the cost is determined by many factors, including the type of car. Usually, labor cost is estimated to be higher than the part cost. Where labor is estimated to be $500 – $600, the part cost can be around $400 – $500, respectively.

Replace faulty timing belt

If you have a faulty timing belt or the component was wrongly installed, ensure to replace the defective timing belt or get a professional auto technician to rectify the incorrect installation of the component.

Diagnose/rectify limp mode

Lastly, if the limp mode is responsible for your vehicle’s poor acceleration, contact an expert auto technician to diagnose the trouble code that may have triggered the feature and fix the faulty part accordingly.


Experiencing no acceleration in a car can be very frustrating, especially if you cannot pinpoint the exact cause of the problem. Meanwhile, although several faults may be responsible for an acceleration problem, it is important to narrow down the issue through careful diagnosis.

Once you can ascertain the exact cause of the problem, fixing the issue will eventually be very easy.

So, if you find someone complaining, “My car starts but wont accelerate,” kindly recommend the solutions provided in this article to such a person or, better yet, refer them to this post.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

Recent Posts