Why the car won't start and what to do about it

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

There are only three global reasons: problems with fuel supply, compression or ignition of the mixture.

Malfunctions due to which the starter does not turn, and methods for their elimination are discussed in detail in a separate article. In this article, we will consider situations when the starter motor works properly, but the engine does not start.

1. The immobilizer is on

What's happening: the starter motor turns confidently, but the engine does not start.

After setting the alarm, the immobilizer control is transferred to it. Sometimes, due to hardware failures or accidental pressing on the key fob in your pocket, anti-theft protection is activated. Depending on the scheme and the selected settings, the immobilizer blocks the fuel pump, injectors, the ignition system or even the starter. In any case, the engine will not start.

What to do: if you accidentally turned on the lock yourself, then try to remove it by finding out the desired combination in the instructions or on the Internet. In case of alarm errors, only an installer or a competent auto electrician can deal with the problem.

2. The battery is discharged

What's happening: the starter cranks the engine, but slowly. Dashboard indicators dim or go out.

Due to the low battery charge, the starter does not spin the engine enough or with difficulty, and there can be no talk of starting. This happens after long periods of inactivity, especially in winter, when the problem is aggravated by thickened engine oil.

What to do: start the car, "lighting" from the neighbor's battery or in one of the other ways, and then charge or replace the battery.

3. Malfunctions of the fuel system

What's happening: the engine rotates, but does not show signs of life.

Naturally, the engine will not start without fuel supply to the cylinders. If there is gasoline in the tank, then most often the reason for the lack of fuel in the combustion chamber is a clogged filter, an inoperative fuel pump or its relay.

Impurities in low-quality fuel clog the mesh of the filter element, and gasoline does not go further. In winter, it can become clogged with frozen water. From this, due to the increased load, the gas pump sometimes fails. It can also break due to overheating when driving with an almost empty tank, since the pump is cooled by the fuel.

What to do: you can only check whether the fuel pump is working. Turn on the ignition and listen. If everything is normal, a buzzing sound should appear in the rear seat area for 5-10 seconds. If the pump is working, but fuel does not flow, then its mesh is clogged.

To clean, replace the filter or the fuel pump, you will have to remove the seat cushion, open the floor hatch and remove the pump housing. If there is no car repair skills, it is better to contact the service.

4. Diesel freezing

What's happening: the engine just won't start.

Fuel that does not correspond to the season on diesel cars thickens strongly in the cold. The paraffins included in its composition precipitate, clogging the fine filter and fuel lines. All this becomes the reason that the engine does not start.

What to do: return fluidity to the diesel engine. To do this, you need to warm up the car in a warm garage or pour a special antigel additive into the tank. After that, drain or use up the remnants of summer fuel and refuel with winter fuel.

Sometimes you can get by with a little blood and warm up with a hairdryer only the fine filter under the hood.

5. Malfunctions in the ignition system

What's happening:the starter turns, but the motor does not even pick up.

In the absence of a spark, the fuel-air mixture does not ignite and, accordingly, the engine cannot start. The reasons lie in punctured ignition coils or wires, as well as spark plugs with a layer of carbon or a cracked insulator.

What to do:the easiest way is to unscrew the candles and visually assess the condition of the electrodes: they must be clean and dry. Then put on the candlestick, attach the candle thread to the metal part of the engine and turn it with the starter. If there is a spark, then everything is in order with the ignition. If not, you need to try other candles, and then check the wires and coils, also changing them to known good ones.

6. Breakage of glow plugs

What's happening:the engine does not start, the spiral indicator on the dashboard is on.

At negative temperatures, the fuel evaporates poorly, and without additional heating with glow plugs, diesel cars may simply not start. A malfunction is usually indicated by a permanently lit coil indicator on the dashboard.

What to do: candles must be removed, checked and defective replaced. For the test, use a multimeter in dial mode. When the probes touch the center contact and the body, a signal should sound.

Alternatively, you can simply supply 12 V from the battery to the candles one at a time. For 3-5 seconds, the electrode of a working candle should warm up red-hot. When not working, accordingly, it will remain dark.

A quick fix is to try to warm up the spark plugs a few times before starting the engine. They do not fail all at once, and if at least a couple is working, then this should help.

7. Sensor malfunctions

What's happening:the starter motor turns, but the engine does not start. The Check Engine indicator on the dashboard is on.

All processes in the engine, including starting, are controlled in modern cars using an ECU. "Brains" read the readings of numerous sensors, and if any of them fails, then the operation of the motor is disrupted or blocked. This is possible due to malfunctions of the crankshaft and camshaft position sensors, as well as idle speed, coolant temperature or knock sensors.

What to do:identify and replace the defective assembly. Unfortunately, this can only be done by specialists in the service. However, if you have an ELM327 scanner, you can try to find the breakdown yourself.

8. Violation of valve timing

What's happening:the starter motor turns easily and the engine does not react at all.

Due to improper adjustment or untimely replacement, the timing belt or chain can stretch and jump a few teeth, or even break completely.

This inevitably leads to a violation of the valve timing: the valves do not close at the right time, compression and ignition of the mixture does not occur. Depending on the design of the engine, the pistons can reach the valves and bend them, resulting in costly repairs.

What to do: check the timing marks. If necessary, install them in accordance with the car operating instructions. For the future: always change the belt or chain according to the regulations and adjust correctly.

9. Offset of the flywheel rim

What's happening: the starter turns idle, a creak and squeal is heard from under the hood.

The teeth, with which the starter bendix engages, are not made on the flywheel disk itself, but on a removable rim - a crown. It is fitted with an interference fit when heated and sometimes, in rare cases, it can turn. In this case, the starter regularly rotates the wreath, but the flywheel itself and, accordingly, the engine does not spin up.

What to do: remove the starter, engage 4–5 gear, and then, locking the crown with a screwdriver, slightly push the car forward or backward. If the engine rotates separately from the crown, then the latter must be removed and replaced with a new one. Perhaps with a flywheel. The procedure is quite complicated and is performed at the service station.

10. Insufficient compression

What's happening: the engine cranks, but does not show signs of life.

The wear of the cylinder-piston group increases the clearances between the walls of the liners and the pistons, as a result of which the compression is greatly reduced. This results in loss of power and difficult starting, especially in winter. The problem manifests itself gradually, and usually the car owner guesses about it.

What to do: measure the compression with a device and decide on engine repair. Without additional equipment, you can make sure of poor compression as follows: unscrew the candles, pour 3-4 mm³ of engine oil into the combustion chambers of two cylinders with a syringe, twist the starter a little, and then put the candles back in place and try to start the engine. If it works out, obviously, the problem is in the wear of the CPG.