The situation when you approach a car, turn the key in the ignition lock, and in response hear only silence or a pathetic click, is familiar to every driver. This always happens at the most inopportune moment: when you are late for a meeting or in the morning on a frosty day. In such seconds, it is important not to panic, but to quickly assess the nature of the sound that the engine emits when trying to start.
Understanding that, Why doesn't the car start?It is often in the details of the starter’s behavior and the state of the onboard network. If the engine is spinning sluggishly or the starter is silent, the problem may be the electrician. If the motor is cheerfully spinning, but does not "grab", the cause should be sought in the fuel supply system or spark formation. Competent primary diagnosis will save you time and money on the tow truck.
In this article, we will analyze all possible scenarios of engine failure, from the banal discharge of the battery to complex mechanical breakdowns. You will learn to distinguish between symptoms and understand what actions you can take yourself, and when it is better to call specialists immediately.
Problems with battery and electricity
The most common reason a car refuses to start is because of a broken or broken battery. In winter, the density of the electrolyte drops, and the old device is more difficult to give the necessary starting current. If you hear the starter’s quieting hum while turning the key, and then the clicks of the traction relay, but there is no rotation of the crankshaft, this is a classic sign of a deep discharge.
However, it is not always the source of energy. Oxidized terminals can create high transient resistance, which simply does not reach the consumer. Visually, it looks like a white or greenish plaque on the contacts. Multimeter It will help to accurately determine the voltage at the terminals of the battery: if it is below 10 volts under load, the launch is unlikely to succeed without an external source.
It is also worth checking the reliability of the attachment of wires "mass". Poor contact of the body with the engine or body with the battery leads to the fact that the electric circuit is opened at the most critical moment.
⚠️ Warning: Never try to light up a car if the hood is protruding battery terminals. A spark can ignite the fumes coming out of the battery, which will cause an explosion.
For a quick diagnosis of the condition of the electrician, it is useful to conduct an external examination. Pay attention to the following points:
- 🔋 The condition of the terminals: they must be clean and tightly tight.
- 💡 Operation of headlights: if they are dim or go out when trying to start, the battery is precisely discharged.
- 🔌 Wire integrity: Check if there are any rubbed sections or breaks in the harnesses.
- 🔋 Battery age: If the battery is over 5 years old, the probability of sudden failure is extremely high.
If you find oxidation, the terminals can be gently cleaned with fine sandpaper or soda solution, having previously shed the contacts. In the cold season, you can try to “wake up” a discharged battery by turning on the high beam headlights for a couple of minutes – this will start chemical processes inside the electrolyte.
Starter and ignition lock malfunctions
If the battery is charged, the terminals are clean, but when you turn the key, a single loud click is heard and nothing else happens, most likely the problem is in the starter. This device is subject to high mechanical and thermal stresses. Most often, the retractable relay fails or the brushes of the electric motor wear out.
Sometimes the starter may fail due to banal pollution. Getting dirt, oil or water inside the body leads to a bendix or anchor jamming. In such cases, periodic taps on the starter body (not a strong blow) can temporarily restore contact, allowing you to start the car to get to the service.
It is impossible to exclude the fault of the ignition lock itself. Contacts inside it can burn, especially if you often use heavy key fobs that create extra load. You can check this by calling the contacts with a multimeter when the ignition is turned on.
Symptoms of starter problems are often confused with battery discharge, but there are nuances. If the starter is buzzing but the engine is not spinning, the teeth of the Bendix gear or flywheel crown may have been broken. In this case, a metallic grinding is distributed.
How to check the starter without removing?
You can close the contacts directly on the retractable relay. If the starter works - the problem is in the wiring or ignition lock. You need to be careful, as the sparks will be powerful.
Let’s look at the main signs of a starter malfunction in comparison:
| Symptoms. | Probable cause | Action |
|---|---|---|
| Single click, silence. | Retractor relay or winding | Check contacts, replace relays |
| Crack, but no spin. | Wear of brushes or bushings | Repair or replacement of starter |
| Unlocked humming | Broken Bendix | Bendix replacement |
| metallic grinding | Wear of gear teeth | Urgent replacement, risk of damage to flywheel |
Ignition system: candles, coils and trampler
When the starter cheerfully turns the engine, but there are no flashes in the cylinders, the problem lies in the ignition system. In modern vehicles with injector For the spark are individual coils or ignition module, and in older models - a tamper and high-voltage wires.
The first thing to check is the spark plugs. If they are filled with fuel ("throwing candles"), the spark will not skip. This often happens after unsuccessful launch attempts. Candles can be twisted, dried outdoors or calcined over a gas burner, after which the gap between the electrodes must be restored.
High-voltage wires and coil tips are also prone to breakdowns. At night, you can see a “spark dance” under the hood if the insulation is damaged. Cracks on rubber caps pass current on the mass, and the energy simply does not reach the candle.
⚠️ Warning: When checking the ignition system on a running engine, never touch high-voltage wires with your bare hands. The voltage can reach 20-30 thousand volts and cause a severe burn or shock.
An important element is the crankshaft position sensor (CRPS). If it fails or is contaminated with metal shavings, the electronic control unit (ECU) simply does not “see” the rotation of the engine and does not give a command to spark. The car in this case will not start in any way, even with a can of "Quick Start".
For owners of cars with a carburetor, checking the trambler runner and the distributor cover is relevant. Oxidation of contacts inside the lid or crack in the plastic (especially in wet weather) leads to the leakage of sparks.
In wet weather, wipe high-voltage wires and coils with dry rags. Use a contact cleaner spray to remove moisture and oxides – this often helps to get the car started in the rain.
Fuel system: pump, filter and nozzles
Without fuel, the engine will not work, and this is an axiom. If the starter spins normally, there is a spark, but the car stalls or does not start, you need to listen to the fuel pump. When the ignition is turned on (before the starter is started) from under the rear seat or trunk, the characteristic hum of the running pump should be heard for 2-3 seconds.
If there is no hum, perhaps the pump motor burned, its relay failed or just the fuse burned. The pump may also not be turned on due to a signal from an immobilizer or an emergency drop sensor (inertial sensor) that is triggered by impacts.
A clogged fuel filter is another common cause of problems. If it is clogged with dirt or water (which is important for poor-quality gasoline), fuel simply does not enter the ramp in the desired amount. The engine can catch, but immediately stop.
In winter, there is a risk of freezing condensate in the fuel line. The water that got into the tank sinks to the bottom and at negative temperatures turns into an ice plug, blocking the fuel intake. The use of special additives-dehydrators helps to combat this phenomenon.
The main elements affecting the fuel supply:
- ⛽ Fuel pump: creates the necessary pressure in the system.
- 🧶 Fuel filter: Retains rust and dirt from the tank.
- 💧 Pressure regulator: Relieves excess fuel back into the tank.
- 🚿 Nozzles: spray fuel into the intake manifold.
If the pressure in the ramp is insufficient, the nozzles will not be able to create the correct spray torch and the mixture will be too poor to ignite. Pressure check requires a special pressure gauge that connects to the fuel ramp connection.
☑️ Diagnostics of the fuel system
Problems with the HRM and mechanical part of the engine
The saddest scenario, why the car does not start, is associated with mechanical damage inside the engine. Breakage of the belt of the timing (gas distribution mechanism) or chain leads to desynchronization of the valves and pistons. At best, the engine will simply stop starting, at worst, there will be a “meeting” of valves with pistons, which will require major repairs.
When the GRM breaks, the starter will turn the crankshaft very easily, with unusually fast rotation and without the characteristic compression resistance. The sound of the spin will become ringing and empty. If you hear this, further launch attempts can only make things worse.
Problems can also be caused by engine jamming due to oil starvation or overheating. In this case, the starter will not be able to turn the crankshaft at all. Attempts to start such a machine will only lead to the combustion of the starter or the break of wires.
Compression in cylinders is a key parameter of motor health. If the compression fell due to the occurrence of rings or burn valves, the engine can start only "from the pusher" and then not always, but it will work unstable, triple and smoke.
If the starter turns the crankshaft suspiciously easily and quickly, do not try to start the car anymore. This can lead to expensive repairs to the HBC.
Climate Impact: Frost and Heat
The climatic conditions have a huge impact on the engine start. In severe frosts, the oil in the engine and transmission thickens, creating a huge resistance to rotation. The battery loses up to 50% of its capacity, and gasoline evaporates worse, forming a poor mixture.
In the summer, in the heat, the problem may be the opposite. Fuel in the tank and highways can boil, forming steam stoppers that prevent normal fluid flow. An overheated engine (if you try to start it after stopping) may also have problems with potassium ignition.
Humidity is another enemy. Rain and fog contribute to the formation of condensation on candles, high-voltage wires and in the air filter. A wet air filter can completely block the air access, and the engine will suffocate.
For successful launch in extreme conditions, it is important to use seasonal technical fluids. In winter, low viscosity oil (e.g. 0W-30 or 5W-40) is needed, and in summer, high-quality fuel with a high octane number is needed to avoid detonation.
⚠️ Warning: Do not use open fires (solder lamps, torches) to warm up the engine or fuel tank. This can lead to explosion of fuel vapor and fire.
Electronic systems and immobilizer
Modern cars are packed with electronics, and often the reason for the failure of the start is a banal failure in the security system. The immobilizer may not recognize the chip key if the battery is dead in the key fob or there is a software glitch. In this case, the key or lock indicator usually flashes on the dashboard.
There may also be failures in the work of the ECU (electronic control unit). “Hanging” of the car’s brains is a common phenomenon after voltage jumps or moisture. In such cases, it helps to reset the battery terminal for 10-15 minutes, which leads the system to factory settings.
Sensors such as DMRV (mass air flow sensor) or DAD (absolute pressure sensor) may give incorrect readings, which is why the ECU prepares the wrong fuel-air mixture. Dirty DMRV often causes the car to start and stall.
Error checks through the OBD-II diagnostic connector allow you to quickly identify an electronic component that blocks the start or disrupts the engine. Even if the Check Engine light is not on, errors may persist in memory.
What to do if you sit down with the key with an immobilizer?
Many cars have an emergency start method: apply the key to a special tag on the steering column or press the brake pedal a certain number of times. Look for instructions for your model.
Frequently Asked Questions (FAQ)
Why does the car start and immediately stop?
Most often this is due to incorrect operation of the idle regulator, sucking of unaccounted air or problems with the throttle position sensor. Low fuel pressure or throttle contamination is also possible.
Can I start the car with a pusher if there is a machine?
It's not recommended. Unlike mechanics, automatic transmission does not have a rigid connection of the wheels with the engine at a non-functioning motor. Attempt to start the machine from the pusher can lead to failure of the gearbox due to the lack of oil pressure.
How often should I change the spark plugs?
Ordinary nickel candles serve about 20-30 thousand kilometers, platinum and iridium - up to 60-100 thousand km. However, the resource is strongly influenced by fuel quality and driving style.
Why does the starter click but not spin?
This indicates that the retractable relay is working, but the starter lacks power to turn the engine around. Causes: battery discharged, terminals oxidized, wear of starter brushes or engine jamming.