Why Does My Car Start Sometimes and Not Other Times?
If your car starts sometimes but not all the time, you may feel like your vehicle is possessed. More likely, though, it’s an indication of one of several common problems that can cause cars to fail to start. Here are a few suggestions for what might be happening and how to fix it:
The battery is going dead.
A car’s battery is essential for a reliable engine start. Like all batteries, your car’s battery will not last forever. After about three to four years of use, most car batteries will require replacement.
The life of a battery may be shortened if the vehicle has been left idle for long periods of time without being started (like during winter storage). In addition, voltage output and temperature can impact the performance of any battery. Most automotive batteries are rated at 12 volts, with cold cranking amps (CCA) and amp hour ratings at other temperatures.
The CCA rating measures the number of amperes that can be delivered at 0 degrees F for 30 seconds and maintain at least 1.2 volts per cell. Generally speaking, a higher CCA rating is required in colder climates due to thicker oil viscosity and increased difficulty moving engine parts during colder temperatures.
Your car may not be getting enough power from the battery.
It’s possible that your battery isn’t getting enough power to the starter when you try to start the car. If you have an old battery, it may not be able to hold enough charge to make starting the car easy for it.
You can check this by using a voltmeter or multimeter. A quick test of the battery with a multimeter will show if there’s any problem here. You should see at least 12 volts from your battery when you do this test. If the voltage is lower than 12 volts, then there’s a good chance that you have a bad or dying battery on your hands and need a new one.
Your car may have a bad starter motor.
The starter motor, as the name implies, is the motor that starts your car. It’s what cranks and turns the engine over to see if it will start. Because it’s an electric motor, the starter needs electricity to work. If it doesn’t get enough of it, then you won’t be driving anywhere.
It’s important to note that the starter motor does not power a car by itself; again, it just gets a vehicle started. That means that if you have a bad starter but your battery and/or alternator are good (more on what those things are in a bit), then you’ll still be able to drive once your vehicle gets going—just not to get started in the first place. The important thing is that these three things—the battery, alternator and starter motor—are all separate components working together with one another so your vehicle can work properly; they’re not one part doing three different jobs.
The fuel pump relay may be bad.
If you have a multimeter, you can use it to test the fuel pump relay. First, open your car’s hood and find the fuse box. Look in the fuse box for a relay that has the same part number as the fuel pump relay. Remove that relay and place it in an area with lots of room to work.
Next, turn on your multimeter and set it to ohms x1000 or whatever is closest to that range. Test for continuity between terminal 30 and 87a on your relay by touching each probe from your meter to each terminal (no need to remove any wires from the terminals). You should get a reading of zero or close to zero. If you get a reading of infinity or anything more than 1,000 ohms, then your fuel pump relay is bad.
Now let’s say you tested the fuel pump relay and found out it was bad—what do you do? Well, I recommend replacing it with one that has exactly the same part number as what was originally installed on your car (I know this isn’t always possible, but try hard!). You can find this information online at sites like Amazon or eBay Motors; just type in your make/model/year along with “fuel pump relay.”
Installing a new fuel pump relay is easy too: simply put the new one back into its socket where you found it in the engine bay fuse box. That’s all there is to replacing a bad fuel pump relay! If however you were testing for continuity between terminal 30 and 87a and got an infinity reading instead of near 0 ohms—or if installing a new fuel pump relay didn’t solve your problem—then go ahead and skip down to our next section: “The Fuel Pump May Be Bad.”
You may have a bad idle control valve.
- If you have a bad idle control valve, it may be preventing your car from starting on some occasions.
- This is because the valve is responsible for controlling the idle speed of your vehicle.
- Your car’s idle speed controls how fast the engine runs when the car is not moving or has just been started up (before you’ve pressed on the gas).
- The idle control valve is usually a computer-controlled electric motor that regulates the amount of air bypassing the throttle plate in order to manage this idle speed.
- When this valve fails, it gets stuck and can cause issues with your vehicle’s idle speed which can cause your car to fail to start.
There are a bunch of different reasons why your car won’t consistently start.
If you’re having difficulty starting your car, don’t worry—there are many different reasons why this can happen. Some of these reasons may be a faulty starter motor, a bad ignition switch, or even one of the numerous relays such as the fuel pump relay. For example, if you have a bad starter motor, the engine will only crank when it feels like it and not always start up. On the other hand, if you have a bad idle control valve (ICV), then your car will typically start with no problem but may intermittently run rough at idle or die out completely.
Whatever the reason for your car’s inconsistent starting is, make sure to get it fixed before something serious happens!