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Why a Car Stalls While Driving And What To Do When It Happens

Why a Car Stalls While Driving And What To Do When It Happens

Next to an outright accident, one of the worst things that can happen to you when driving is having your engine stall. The danger of a stalled engine is that you can lose control of the vehicle and have an accident hurting yourself or someone else. If your car does stall you need to know why it happened and what you can do about it. Knowing how to prevent a car that stalls while driving is also key to avoiding what could be a costly and dangerous issue.


 

What Happens When a Car Stalls While Driving?

 

On paper a stalled car sounds like a car that just doesn’t move, but what does it mean for you as a driver if your car stalls while you’re actually driving it? What are you going to experience? If your engine stalls while driving your power steering will be the first thing you notice is not functioning properly any longer. When power steering dies, the wheel can still move, but it is much harder to do. This will be followed by the power brakes and the brake pedal will no longer be responsive underfoot. This is going to make it very hard to control the car but not utterly impossible.

 

If your power brakes and power steering fail as a result of a stalled engine, you should still be able to apply the handbrake and steer towards the side of the road. Put your emergency lights on and proceed as carefully as you possibly can.

 

If the car stalled while you were at a stop sign or a red light, put on your hazard lights and if you can steer to the side of the road do so. If you can't, which is likely, call for help. You can push the car to the side of the road if it's safe to do so but if you’re in a high traffic area you’re safer to stay put with those hazard lights on until help arrives. Pushing a car in traffic is dangerous.

 

If it’s late, you may want to put out road flares if you have them for increased visibility. During daylight hours you can also pop the hood of your car when you're safely to the side of the road for added visibility that will let other drivers know you're in distress.

 

When you’re safely on the side of the road, you’re going to want to disengage the parking brake and leave your car in neutral. This is a safety precaution in case you were to be hit by another car. The impact will be greatly lessened if your car is free to move rather than a brick in the way.

 

Why Does a Car Engine Stall?

 

There are potentially a number of factors that could lead to your engine stalling on you. To begin with, a stalled engine is an engine that has stopped working entirely, causing the car to stop working. This could be the result of something as simple as your car being out of gas, or one of these more in-depth issues;

 

  • A poor fuel mixture. If your fuel isn’t rich enough, which is to say you don’t have enough fuel compared to air for combustion. This can be caused by damaged fuel lines, blown gasket heads, or other issues.

 

  • No fuel. Not the same as having an empty tank of gas, you may not be getting any fuel if you have a plugged fuel filter or dirty fuel injectors. Less likely but still potentially an issue is that you have the wrong fuel in the car, such as diesel. .
  • Fuel mixed with water: Sometimes moisture will contaminate a fuel mixture and that can cause your engine to struggle and stall out. If you’ve found that your engine is struggling only since you last filled the tank, this could be the problem. If that’s the case, you can either have the entire tank drained or try to burn through the whole tank. You may be able to run the engine on the contaminated fuel mix, just with some difficulty. If you can use all the fuel and refill then run with no problems, that means this was probably the problem.
  • A faulty fuel pump. If your fuel pump is no longer working properly the car will not start at all. This is simply because the fuel has no way to get to the engine to begin the combustion reaction.
  • Distributor cap issues. Since the distributor cap delivers voltage to the spark plugs in your engine, if there is a problem with a cap your engine could suffer as a result. Bad wiring or maybe clogged rotors in the distributor can lead to poor spark or no spark. You can give this a quick look to see if the cap is corroded, dirty, or damaged in any way to get an idea as to whether this may be your problem.
  • Bad spark plugs. Related to your distributor cap problems, you could have bad spark thanks to fouled spark plugs. Corrosion, damage and just general wear and tear could have ruined the integrity of your spark plugs and other electrical systems. If they’re not running at optimal then your engine could be stalling.
  • Sensors in your car reading hot or overheating. You should have some advance warning of this as it’s very rare for a car to get hot enough to stall the very first time it happens. If your engine has a habit of running hot, this could be a side effect though as it gets so hot it stalls out. Your best bet is to address this overheating issue before it gets so bad the engine stalls but if that ship has sailed, you’ll need to let the engine cool down and add some coolant once it is safe to do so. Wait about 15 minutes then carefully try to add coolant and see if the car started again. From there, you'll want to get the overheating issue properly diagnosed.
  • Your battery has died. This is one of the more common reasons for engines to stall out. If your battery is 100% dead your car will not even start to stall out in the first place. That said, a battery has a period of time between working well and being dead. When the battery is dying, that’s when you’re at risk of the car stalling out intermittently, even while driving. That low power output from your battery means your alternator has to work harder to keep your car running. That puts more stress on the engine and the car will stall.
  • Your air filter has become so clogged it’s preventing proper airflow. If the filter has sucked in too much dirt or debris, the restricted airflow can cause an engine to stall. Air filters have a lifespan of about three years. If you haven’t changed yours in that long or longer then it’s possible this is the issue you’re facing.
  • Low fuel pressure. The easiest way to diagnose this issue is through observation. If your car runs fine on a flat road but you find it stalling out as you go up and down hills, then you likely have an issue with fuel pressure. When the tank is at an angle, the pressure isn’t high enough to keep it pumping properly, and the engine stalls out. Some fuel injector cleaner might be able to fix this issue.

 

  • Faulty sensors. Modern cars rely on numerous sensors to function properly and when the sensor data goes wrong, the engine may stall as a result. Faulty camshaft or crankshaft sensors can relay the wrong positioning data and throw off your engine timing. The mass airflow sensor could be sending the wrong signals about air in the engine as well. Any of these could malfunction due to damage or by being dirty.

 

How Often Do Car Engines Stall While Driving?

 

Thanks to improvements in technology you could make a case that every issue, including stalls, is happening less and less often these days. Car engine stalls were once much more frequent than they are today but that’s a relative term. They still happen far more often than any driver would like. In fact, according to Consumer Reports, from October 2018 to July 2019 over one million vehicles in the US were recalled for issues relating to stalls.

 

What Does It Cost to Fix a Stalled Engine?

 

Once you've gotten your car safely to the side of the road, you’re going to want to get your car to the mechanic as soon as possible. Even though, as we’ve seen there, are literally dozens of potential reasons for an engine to stall, none of them are good and they aren’t the sorts of problems that work themselves out naturally. It’s very likely that, with the exception of stalls caused by moisture in your gas tank, your car will keep stalling if you don't get the issue properly diagnosed and fixed. The longer these repairs are put off the more likely the problems are to keep happening and the more likely they are to get worse as well. You risk a greater repair bill down the road, not to mention the chance of more accidents.

 

The number of potential causes of engine stall means that diagnosing the problem could take a while. The cost for repairing the issue is just as varied. A simple spark plug replacement could be relatively easy to diagnose and inexpensive to repair, maybe setting you back $100 to $200 if you get it done by a mechanic. But sensor or fuel pump issues could be much more costly. You could be looking at a wide range from $200 up to even $2,500 or more. Only a proper diagnosis of the issue will let you know for sure.

 

Can I Prevent My Engine from Stalling?

 

The best way to prevent engine stalling is proper maintenance of your car beforehand. Because there are so many reasons why your engine may have stalled to begin with, a routine schedule of maintenance is needed to negate most of them as concerns. That means making sure you have coolant and oil levels topped up on a regular basis, as well as changing your air filter.

 

Make sure you are using the right fuel when you gas up and keep your car clean to try to prevent sensors and filters from getting clogged and soiled. If you notice issues like overheating, your car jerking or power fluctuations, have those addressed when you see them instead of putting them off. The last thing you want is for a $50 problem to become a $500 problem because you let it slide for a month.

 

Additional Safety Concerns of a Stalled Engine

 

Safety is your main concern when your engine stalls so you need to be aware of what could have gone wrong. As we’ve said, you want to make sure your hazard lights go on right away and put up road flares if you have them. Be aware that power steering and brakes will be out. Depending on what happened, you might have also lost things like airbags and other safety features. Without those to rely on your car is much less safe in this condition than you’d at first think.

 

You need to be both as visible as you can and as out of the way as you safely can when your engine is stalled. If you’re stuck in traffic, stay inside the car and don’t attempt to leave to the side of the road. It’s safer for you inside than trying to weave through cars outside.

If your car stalls on a bridge you’ll want to leave the parking brake on in this case and wait a few hundred yards ahead of your car on the bridge path catwalk for help to arrive, only because the accident potential on a bridge would be so much more devastating because of the location if you were to stay in the car or leave it in neutral.