Your car may not be starting for a variety of reasons. Your battery might be weak, your starter might be old, your alternator is probably old, your ground connection could be bad, you could have a short in the starter circuit or a bad connection in the positive power feed to the starter. You could also have corrosion within the connections at the alternator.
To troubleshoot why your car doesn’t start sometimes and other times it does, you will need an assistant to turn on your headlights while you crank it over. If they dim when it cranks over but stays bright when it doesn’t then that’s the clue that you need more amperage to crank over your engine. If they stay bright both times then you will need to check for spark at one of the spark plugs. If there is no spark and only sometimes there is power going to your ignition coils then you’ll know that part of this problem has been resolved!
The car is old and the battery is probably too weak.
The electrical system in the car has a battery to store electrical power. The battery’s job is to provide enough current to crank the engine and keep everything running after it starts. If the battery doesn’t have enough stored energy, it can fail to start the engine.
It might be that your battery just isn’t strong enough to start your car anymore (or maybe it’s not even supplying any power at all). Check your battery voltage with a voltmeter, and replace it if it’s under 12.5 volts.
There is some internal corrosion in the starter that works itself loose over time.
The corrosion can cause problems with your electrical connections. The corrosion can increase resistance and make it harder to get a good connection for electricity to travel through. Corrosion is caused by water or other contaminants and is worse in cold climates.
You can fix this by cleaning the connections with a wire brush, steel wool, sandpaper or even using a spray that removes corrosion. You can also use grease on the terminals after cleaning them so they will not corrode again as quickly.
The alternator is starting to fail.
There are a few things you can do to determine whether or not your vehicle’s alternator is on the fritz. You’ll first want to check the output of the alternator and make sure it’s charging correctly. While most vehicles come with a tester, you may want to buy one separately so that you don’t run out of battery power while testing your alternator. Once you’ve got everything set up, turn your vehicle engine over for about 20 seconds and then check the voltage at both battery terminals again. If everything looks good, you’re all set!
There’s a problem with the ground connection between the engine and frame.
Your next step is to check the ground cable from the engine to the frame. It could be that moisture or dirt has built up, corroding the connection and leading to a poor grounding of your vehicle. Look for loose connections as well; you’ll want to make sure that your ground cable is securely in place. Finally, check for damage on your ground cable; if it looks worn down or broken, it’s time for a new one.
There’s a short at one of the relays in the starter circuit.
The relays in your starter circuit are used to switch high-current circuits on and off. These circuits are often operated by low-current signals (switches, computers, timers). Usually there is one high current circuit, and one low current circuit per relay. The relay receives the signal to open or close the switch, and acts as a remote control for that switch.
There’s something wrong with the ignition key and ignition switch.
There’s something wrong with the ignition key and/or ignition switch. When you turn the key, it causes a series of events to happen in your car. It sends power to the starter motor, which then starts up the engine and turns on all of those lights on your dashboard. If any one of those things doesn’t happen when you turn your key, then the problem is with either your key or ignition switch.
If you can replace the entire ignition lock cylinder (which usually consists of both of these components), then do that. That’s always going to be your best bet because it’s an all-in-one approach that will ensure everything works as it should. However, if that isn’t possible, then at a minimum you should replace either just the ignition switch or just the ignition key itself.
No matter what solution you go with, don’t try to clean or lubricate anything! That doesn’t work in cars and never has worked in cars. Instead, buy new parts for whatever piece is bad, then install them yourself (or have a certified mechanic do it).
There’s a bad connection in the main positive power feed from the battery to the starter.
The first thing you should do is check the connection between the battery and the starter. If you find a bad connection (or even two), clean it up using some sandpaper and a little elbow grease, then re-connect it. To make sure that there’s nothing wrong with the wiring in your car, you can use a voltmeter to run a current through all of the wires going from the battery to start your engine.
Now, if everything looks good but your car still refuses to start, then I would suggest checking all of your fluids. Your brake fluid, oil and coolant levels should be checked regularly just as part of basic maintenance on any vehicle.
The temperature sensor in my car has gone bad and it is causing problems with starting at higher temperatures.
The temperature sensor in your car is responsible for telling the engine control unit (ECU) what the engine’s running temperature is. The ECU can then adjust the air/fuel mixture to accommodate the change in temperature.
When this sensor goes bad, it may stop transmitting proper information to the ECU. Without accurate information, the ECU won’t know if it needs to make adjustments and will continue using whatever setting it was last programmed with. To prevent any damage, it may err on the side of being overly rich and flood out your engine. If you start your car immediately after this has happened, you may experience difficult starting or stalling once you’ve got it started. As a result, starting your car at higher temperatures or trying to restart after a stall can be problematic.
In most cases, replacing this part is fairly easy and affordable; parts only cost around $20 USD and can be installed without special tools or training by following an online tutorial video or guide.
You need to clean the connections to your alternator and check them for corrosion.
Even if your vehicle is running well, it’s important to note that regular maintenance can help you stay on top of any potential problems before they get worse. When you notice a problem, such as a starting difficulty or stalling, it could mean the battery isn’t charging the way it should be—and this could indicate an issue with the alternator. If your alternator is bad, there are a few different methods to clean it. One method requires disassembling the alternator and cleaning all parts individually, which may be too costly for some people; however, if you have the tools and supplies available to perform this method properly, you can learn how to do so here. You will still need to check for corrosion when reassembling.
Another option is using chemicals that are designed specifically for cleaning car batteries and other electrical components. These products cost under twenty dollars at most auto parts stores and can safely be used on anything electrical in your car. When using these types of chemicals, follow instructions closely; they’re easy to use but should not be ingested or left near open flames because they contain corrosive acid!
It is difficult to identify why your car sometimes starts and sometimes doesn’t without a proper diagnosis but these are some possibilities
Whatever the cause, there are a couple of things that you can do to get your car running again. First, you’ll want to make sure that the car is plugged in and that its battery is fully charged. Next, check for any loose connections or corrosion around the terminal where the battery attaches to the car. If necessary, clean out the connections with a wire brush or other tool to ensure good contact between your vehicle’s battery and its electrical terminals.
If these steps don’t seem to be doing anything, then you may need professional help. However, if you have one of these problems often then there could be a simple answer: have you changed your ignition switch recently?
