Car Struggles To Start but Runs Fine (Reasons & What to do)

It’s a familiar sight. You wake up and go through your normal morning routine only to find that it’s difficult to get your car started in the winter.

It’s a common problem for many car owners, but many don’t take the time to figure out what’s happening or why it’s happening in the first place.

But for those that take the time to figure out what’s going on, figuring out why your car struggles to start but runs fine can be both frustrating and perplexing.

Even worse, ignoring the problem typically leads to more problems down the road. Maybe the cold weather just hit, or perhaps it’s a problem your car has had for a while.

Either way, if your car struggles to start but runs fine, you’ve come to the right place. We’ll walk you through everything you need to know to get your vehicle starting up on the first crank every time.

6 Reasons Why Your Car Struggles to Start but Runs Fine

If your car struggles to start but runs fine, you need to figure out the reason for it as soon as possible. That’s why we wanted to highlight six of the most common reasons this might happen right here at the beginning.

1. Battery Problems

Any time your car is struggling to start but runs fine, one of the first things you’ll want to take a look at is the battery. That’s because the car battery provides the necessary electrical power to the starter motor to start your vehicle.

A faulty battery won’t have the necessary power to turn over the starter, but once you get the vehicle started, you rarely experience problems.

While it’s common to check the battery voltage to determine if you have a bad battery, that doesn’t give you the full picture. A failing battery can have lower than the necessary 12.6 volts of electric power, but it’s also possible that it has near a full charge but still doesn’t work.

That’s because a car’s battery also needs the right amount of amperage to push that voltage through the rest of the electrical components. Because of this, we highly recommend using a comprehensive battery tester instead of a simple voltmeter when checking a battery.

You also might notice that your battery has more problems during cold weather, which is perfectly normal. However, a battery struggling to start your vehicle during the winter likely won’t last much longer.

2. Alternator Problems

While your car battery supplies power to the starter motor, it only has so much power to go around. The battery relies on the vehicle’s charging system to restore the battery power, which falls down to the alternator.

Even if the battery is perfectly fine, you’ll still find that it keeps dying on you and making it hard to start your vehicle. Eventually, a faulty alternator can even lead to your car dying while you’re driving, but it usually takes a while for it to get to this point.

Related: How Much Is an Alternator? (With Repair & Replacement Cost)

3. Starter Motor

While the battery and the alternator work in tandem to get power to the starter, if the starter motor isn’t working correctly, none of that matters.

Sometimes when the starter motor fails, the vehicle won’t start at all, while other times, it will only start intermittently. It all comes down to the exact problem with the starter.

If it fails completely, it won’t start at all, but if it’s only missing a few teeth, then sometimes it will grind instead of start.

Either way, you’ll want to replace the car starter before the problem gets any worse and leads to further damage.

4. Wiring Systems

The battery provides the power, the alternator charges the battery, and the starter starts your vehicle, but none of that happens if your car can’t get the power from the alternator to the battery and then the battery to the starter.

That’s the job of the wiring system, and loose wire connections or battery cables can completely derail the entire electrical system.

Battery terminals are a common cause of loose wires since they often come on and off, but any loose or crossed wires in any of the electrical systems in your vehicle can create these problems.

Most often, this comes from a parasitic draw, which is when an electrical component doesn’t completely shut off when turning off the vehicle so it keeps draining the battery.

5. Ignition Switch

In order to start your vehicle you need to either press a button or turn a key to start your vehicle, and no matter what method you’re using there’s a starter switch working behind the scene.

The starter switch is an electrical switch that’s a part of the ignition system and it’s what kick starts the whole process of sending voltage from the battery to the starter.

If this component isn’t working properly, your vehicle won’t know that you want to start it. Of course, once you do get it running, you won’t notice any problems!

Related: 6 Bad Ignition Switch Symptoms (& Replacement Cost)

6. Starter Relay

While it’s rare that a relay fails, it is a possibility. When you turn the key in the ignition, you should hear a “click” coming from either the engine compartment or the passenger side of your vehicle.

This is the starter relay clicking over and sending power to the right components. If you can’t hear that click, the problem might be the starter relay.

Other Reasons Your Car Might Struggle to Start

While those are the six most common reasons your car might struggle to start but run fine, other engine components might be causing problems that make it challenging to start your vehicle, but they’ll usually lead to some kind of noticeable conditions when you get it running.

Fuel Pump

Your engine needs fuel to both start and run, but not just any fuel will do. The engine needs to avoid low fuel pressure and get the right fuel and air mixture, and getting enough fuel from the fuel tank to the combustion chamber is the fuel pump’s job.

The fuel pump is an integral part of the fuel system, but fuel pumps are also one of the most likely components to fail. Replacing a bad fuel pump is essential if you want your vehicle to start up consistently and stay running.

Other Fuel Problems

While the fuel pump might be the most common component to fail in the fuel system, there are plenty of other potential problems in the fuel system that could be causing your vehicle problems.

The fuel pump takes fuel from the gas tank to the fuel injectors by pushing it through the fuel lines. If there’s a problem with any of these components there’s going to be a problem with the final fuel supply, and your vehicle won’t get sufficient power.

Another thing you need to keep in mind is where you’re purchasing your fuel. Typically, only diesel engines have a fuel filter, and lower fuel quality can certainly impact how easily your engine starts or how it performs once it’s running.

Also, keep in mind that even fuel filters can’t compensate for lower-quality fuel. Do yourself a favor and buy good quality fuel, even if it is a few cents per gallon more expensive.

Spark Plugs

In a gasoline-powered internal combustion engine, spark plugs are what start the combustion process inside the combustion chamber. But over time, gunk can form on the tips of the spark plugs, and the spark plug gap can widen, leading to performance problems like misfires.

This process pushes the pistons down in the engine cylinders, and it’s what generates power for the entire engine.

But while all spark plugs might look the same to the inexperienced viewer, these small devices are rarely plug-and-play. Not only do they need to thread into the exact size opening for your vehicle, but different vehicles can use different gaps.

Moreover, different spark plugs last different amounts of time, so if you spend a little more for higher quality spark plugs now, you might be getting the better deal in the long run.

Getting the right spark plugs in your vehicle is essential to ensuring that your vehicle runs as it should, mile after mile.

Ignition Coil

In order to fire and spark the right way, the spark plugs need 12,000 to 25,000 volts of energy. The battery only has 12.6 volts to give, which means you need something that can multiply that voltage for your vehicle to run.

That’s the job of the ignition coil. A faulty ignition coil won’t get the necessary voltage, which can lead to misfires that can make it difficult for your vehicle to start or stay running.

The ignition system also relies on the correct ignition timing, but the exact method to determine this varies by vehicle. Some vehicles use a distributor cap to control ignition timing, while others have a distributorless ignition system.

Air Filter

While having your car struggling to start and stay running, it often comes down to fuel and ignition problems, but that’s not the only other potential cause. The engine needs to get the right air-to-fuel mixture for the combustion process to work as it should.

This all starts with the air filter. The filter keeps contaminants from getting into your engine, but if the filter is too dirty, it won’t let enough air into the system.

It could also be a problem with the intake or throttle valve, but these issues are typically a little less common.

Diagnosing Why Your Car Struggles to Start but Runs Fine

Now that you know a little more about the potential reasons your car struggles to start but runs fine, it’s time to move on to how to figure out what’s actually going on with your vehicle.

For this guide, we’re going to focus solely on the causes from the top of our article, simply because the other issues should lead to problems while you’re driving too, which will help you pinpoint the problem.

But if your car struggles to start but runs fine, this troubleshooting guide is for you.

Car Struggles To Start but Runs Fine Troubleshooting Guide

The first thing you’ll want to rule out is the charging and starting system. Part stores like AutoZone will test your battery, starting, and charging system for you for free, and the test is usually pretty accurate.

However, what the technician might not tell you is that the test is only completely accurate with a fully-charged battery. So, if the machine says to replace any of these components, do yourself a favor and charge the battery back up and test it again.

Moreover, the part store attendant isn’t a certified mechanic, and they’re not going to go through and troubleshoot everything for you.

Because of all this, we highly recommend having one of these technicians test your vehicle, but then you should use the information they give you as a starting point for potential repairs.

If the problem comes out as a bad battery, ensure it’s fully charged, then test it again. If it still says the problem is the battery, most likely that’s the problem.

If the machine tells you the problem is either the alternator or the starter try gently pulling on the battery terminals to see if they move around, if so, tighten them down before doing anything else.

This could be the problem, but the real reason we want you to do it first is that it’s so easy, and we don’t want you to complete a ton of troubleshooting only to figure out the problem was a loose battery terminal.

If the machine says there’s a problem with the alternator, we highly recommend getting a volt meter and testing it for yourself. Hook up the positive lead of the multimeter or voltmeter to the backside of the alternator on the output wire and the negative lead to a good ground.

With the engine running the alternator should put out between 13.9 and 14.8 volts. Any other reading signifies a problem with the alternator, and it’s time to replace it.

If the machine says there’s a problem with the starter motor, you should bench test the starter. Remove the starter from your vehicle and put it into a vice. From there, supply 12 volts of power to the starter while grounding it out.

The spline inside the starter should “kick out” and start spinning. You can also try applying a little pressure on the spline by using a pry bar to ensure it has the force to kick out when it hits a little resistance from the flywheel.

If either the alternator or starter checks out, then there’s a good chance the problem is electrical. Listen for a click to rule out the starter relay. If you can’t hear the click, swap out the starter relay for a different one in the vehicle.

If the problem “moves” to the new system, you know that’s the problem. If it doesn’t, you either have a problem with the ignition switch or there’s a wiring problem.

Check for power at the relay to see if it changes when you try to start the vehicle. If it does, it’s a wiring issue after the relay.

If there’s no power there, then the problem is before the relay, and it could be the ignition switch.

Final Thoughts

If your car struggles to start but runs fine, it could be a lot of different engine components leading to the problem. Hopefully, after reading through this guide, you have a better idea of why your vehicle is having trouble starting even if the engine is running fine.

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Rickard Cefalk

Rickard is the owner of and a dedicated and avid do-it-yourselfer who has always enjoyed working on his own vehicles since childhood. He now devotes his time to sharing his expert knowledge of car maintenance and other car-related information through his website.

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