It’s everybody’s most mundane nightmare—you go out to start your car, and the car doesn’t run. It looks like you need a jump start. It’s a common problem that almost everyone runs into at one point or another after learning to drive. Still, few drivers understand why this happens – unless they also happen to be mechanics.
So, what are some of the reasons cars need to be jump started? The most common reason a car might need to be jump started is a weak or dead car battery. This is what most drivers run into, especially in cold weather. Other problems that could require a jump start are malfunctions in the starter or alternator, dirty spark plugs, and clogged fuel lines.
Knowing the potential causes of a car not starting can help you determine your next step if this ever happens to you. Read on and find out more about the different reasons a car might need a jump start.
5 Car Problems That Lead to a “No-Start” Scenario
There are several different kinds of car problems that can ultimately lead to a car not starting when you turn the key in the ignition. Most of them are related to the ignition system, or the part of the car that fires the engine under electronic command from the key in the lock and cylinder.
The first assumption most people have when they have to jump start their car is that the battery died, and it’s a good one—it’s the most common form of trouble you’ll run across that can cause your car to have problems starting up. If the car doesn’t start after being jump started, though, you might be looking at some more complicated mechanical problems than a simple battery swap.
Here are the most common forms of car trouble that can lead to a driver needing a jump start:
- 1. Dead or weak battery: Car batteries don’t last forever, and in cold conditions, an older battery can go dead quickly. Even if the battery still has a little power left, cold temperatures or merely old age may eventually lead to the battery not having enough juice to power the ignition system. This problem is usually evident when the driver attempts to start the car cold. If the battery is not entirely weakened, it may increase in efficacy after the car has been warmed up, leading to an intermittent start-up issue.
- 2. Malfunctioning starter: If your battery tests okay and you still can’t get the car started without a jump start, the problem is likely in the starter itself. The most surefire symptom of a starter malfunction is a telltale clicking noise whenever the key is turned in the ignition. However, a starter can also die without making any noise at all. It might also be a bad starter if the car won’t start even after a jump start. Starters can malfunction as a result of corrosion from old age, fraying or loose electrical connections, or even oil contamination from a leak.
- 3. Clogged or frozen fuel lines: When you have a clogged or frozen fuel line, you may be able to get the car started momentarily, but the car will begin stalling and hesitating almost immediately. This is because, with clogged or frozen fuel lines, the car isn’t getting enough fuel in the system to keep the engine running. If a car can catch enough to start the engine even for a few seconds, it is less likely to be related to either the battery or the ignition system and more likely to be fuel system related.
- 4. Fouled or bad spark plugs in the ignition system: Along with the alternator, the ignition switch, and the starter, the spark plugs are a part of the ignition system that can prevent the car from starting if they are malfunctioning. Spark plugs often become non-functional after being contaminated by an oil leak or other fluid leak in the engine compartment.
Since spark plugs are a somewhat delicate electrical component (and cheap), it doesn’t take much to cause a misfire in the spark plugs if they’re older or damaged. Changing them out as a set is an excellent way to troubleshoot a no-start problem that has been determined to be unrelated to the alternator, starter, or battery.
- 5. Alternator malfunction: Bad alternators are almost as typical as bad batteries when it comes to cars that won’t start. The problem with a bad alternator is that, while a battery that takes a jump start might keep a car running for a short amount of time, the lack of a functioning alternator means that the car won’t be able to maintain a charge for long.
Alternator problems are often diagnosed once a car’s battery is determined to be operational, yet still won’t hold a charge. You can often see more subtle indications of alternator trouble before the car completely fails to start, such as indicator lights in the dashboard or electrical problems such as a flicker in the headlights.
Many other issues can cause a car to refuse to start beyond these five reasons, but these are some of the most common ones you’re likely to run into in your own driving experience. If troubleshooting any of the above systems doesn’t yield results, the problem is likely something more obscure, such as an electrical malfunction.
When A Car Can’t Be Jump Started
Sometimes a driver will think that their car battery is flat and get a jump start only to find out that the jump start can’t get their car going again. A jump start is typically only useful if a car’s battery is dead or the alternator is bad—many other issues with a car’s ignition system will prevent a car from being started even if a jump start is provided.
These are some of the systems that may be involved with your car if a jump start doesn’t solve the problem:
- Fuel system: When a car won’t start because of the ignition system, the engine typically won’t catch at all. But when a car does not remain running after being started, that points to a different cause entirely. In many cases, it is related to the fuel pump or fuel lines. Also, if the fuel gauge malfunctions, this can lead the driver to believe that their car has gas when it doesn’t.
- Lock and cylinder: If a key can’t seat fully into the lock and cylinder because of wear or some malfunction within the mechanism, sometimes the car’s electrical system can’t register that the driver is trying to start it, and this can cause a no-start issue.
- Security lockout: Aftermarket security systems on newer, more electrically sensitive models can often cause malfunctions within a car’s electronics, ultimately leading to a security lockout. A faulty anti-theft system can be one possible culprit if you’re looking at a no-start problem with no other likely suspects.
- Electrical issues: Electrical shorts in a car’s systems can lead to a no start issue, and this can, unfortunately, be one of the most challenging problems to track down and correct if it is the root of the trouble. Electrical diagnosis often involves tracking each of the car’s circuits individually until the faulty circuit is found and replaced. Because of the amount of time needed to diagnose electrical issues, this kind of repair is costly.
While a driver can sometimes replace the battery or spark plugs on their car easily enough to get the car running without a jump start, looking into these other problems in the case of an intermittent start or start failure involves more intensive diagnostics that are best left to an automotive technician.
A professional knows how to read error codes in the car’s electrical system and can pinpoint the location of the problem much quickly than a layman can.
Can Jump Starting Damage a Car?
Many drivers are reluctant to try to jump off their car if they aren’t familiar with the procedure for doing it because of the threat of accidentally causing damage to the vehicle’s electrical systems if it is done incorrectly. While it’s a relatively simple procedure, the high voltage involved combined with the technical knowledge necessary intimidates some people out of ever attempting it.
This is a realistic fear, as a jump start—even when performed correctly—can damage one or both cars involved. Accidentally connecting jumper cables in reverse can damage the battery of either car by causing a sharp spike in surging voltage.
The threat of damage isn’t limited to jumping off cars improperly, however. Just the effort of trying to start the second car can cause transient voltage spikes capable of damaging the more delicate of a car’s electronics systems, especially if they are aftermarket systems without surge protection.
To help reduce the chance of causing unnecessary damage to the electrical system of either car, it’s a good idea to turn off all auxiliary electronics while jumping a car off, including the headlights (which are particularly susceptible to electrical damage from over voltage).
Using a jump starter battery can be one of the safest ways to jump start a car. I bought a battery jump starter that has worked for me several time when my car failed to start. Once you learn how to use it, it's fairly simple and has worked well for me.
I've found that you do need to make sure that the battery is charged all the way for it to be effective, since a low starter battery won't work on all occasions. The nice thing is you can charge it in your car from a USB port.
How to Safely Jump Start a Car
If you find yourself in a position where you need to jump start your car, you must know how to do so safely. Cars run on a high enough voltage to cause severe injury or death to a person if they accidentally touch a live wire.
The following steps walk you through the method for jump starting a car safely:
- 1. Make sure both vehicles are turned off, and all auxiliary electrical systems are switched off.
- 2. Identify the positive (+) battery terminal on the battery of both vehicles. The vehicle battery should have a positive and negative terminal. You must not mix these up while performing a jump start.
- 3. Clamp the positive red jumper cable (+) to the positive battery terminal of the dead car’s battery. Clamp the other positive red jumper cable to the positive battery terminal on the functional car that you’re getting a jump from.
- 4. Clamp the negative black jumper cable (-) to the negative battery terminal post of the functioning car’s battery. Note: DO NOT clamp the other black jumper cable to the negative battery post on the dead car’s battery terminal. This can cause an explosion or significant electrical damage.
- 5. Connect the remaining black negative cable to a bare metal surface under the hood of the non-functioning car. This will act as the electrical ground.
- 6. Start the functional vehicle and allow it to idle for five minutes. Disconnect the jumper cables entirely before attempting to fire up the non-functioning car.
- 7. If this doesn’t start the car, attempt to attach the grounding cable to a different area beneath the hood of the non-functioning car for a better connection, or press the accelerator on the functioning car to gas the engine and increase power output. Then try starting again in a few minutes.
Hopefully, at this point in the process, you will end up with two working vehicles that run.
If you don’t specifically remember leaving on your cabin lights or some other operator error that might have accidentally run your battery down, this is the point when it’s a good idea to run your car over to the auto shop (while it’s still running) and see if a mechanic can at least test your battery and alternator for you.
Keep in mind that if your car’s starting problem is an alternator, that jump start is only going to last to your next destination.
Jump Starting a Car Doesn’t Always Fix the Problem
A jump start can temporarily solve the problem of getting from point A to point B if you discover your car won’t start, but for many car problem scenarios, it is only a bandage for the issue, not a cure.
Only in some situations, like if you leave your interior lights on overnight and run your battery flat, can you jump start a car’s battery and not experience any further issues with the car starting again.
Once you’ve managed to get your car jump started, the first place you should drive it is to an auto repair shop so that a real professional can take a look at it and figure out what the source of the malfunction is. At the very least, if you had to jump your car off after running your battery dead, a mechanic can verify that the battery still has enough power that it doesn’t need replacing.
It’s essential to address the problems causing a car to need jumping off for a few reasons:
- These kinds of car repair issues can become worse if they are neglected. This can lead to more massive repair bills and a longer time for the car to be stuck in the shop when it finally breaks down for good. It’s better to get a car’s mechanical issues addressed while it is still running rather than waiting for it to break down entirely.
- A car with an intermittent starting problem can end up with an intermittent stalling problem. Once a car has begun to stall and hesitate in the middle of traffic sporadically, an annoying and inconvenient situation becomes a more dangerous one.
- It might leave you stranded next time. Just because a car can be jump started once doesn’t mean it will be capable of being jump started again, so if you’ve got an intermittent start problem with your vehicle, it isn’t something that can be put off without risking being stuck without a ride.
- It’s terrible for a car to do it all the time. As mentioned in the previous section, the high voltage from jump starting a car can potentially do damage to its electrical systems, so it’s a good idea to limit jump starting to as few incidences as possible to limit the chance of lasting damage.
- You might not be able to find a jump-off next time. Just because you happened to have jumper cables in your driveway and a neighbor’s car the first time your car fails to start doesn’t mean you’ll be in such a convenient situation next time. It isn’t worth the uncertainty of not knowing whether you’ll be able to depend on your vehicle for regular transportation.
The most important thing to remember is that a jump start is just to give your car enough power to get you to a mechanic. It isn’t a method to rely on to limp your car along for days or weeks. This isn’t just a matter of convenience, but a matter of safety as well.
Learning to Jump Start a Car Correctly Can Be a Useful Skill
Knowing how to jump start a car (and more importantly, having the tools on hand to pull it off and the gumption to attempt it) can quickly take some out of that knee jerk anxiety of finding out that your car won’t start. But unless you know how to do so correctly, you can potentially cause more problems than you solved. Not only that, but you can also potentially damage someone else’s car in the process.
Jump starting a car also doesn’t solve some intermittent starting problems permanently. Only further mechanical diagnosis and repair can eventually fix the problem for good.
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