Malfunctions that appear at the time of starting the engine are quite common during the operation of a vehicle, regardless of the type and design features of the installed power unit (gasoline, diesel, or engine, etc.). One of the most common situations is that after turning on the ignition and turning the key in the lock to the start position, the starter turns normally, but the engine does not start.
A feature of this kind of breakdown is a certain complexity of fault localization. The fact is that it is much easier to look for a problem if, for example, the starter makes a sound, but does not turn the engine, or the gas pump does not pump after turning on the ignition. In any case, the existing problem needs to be solved. Next, we intend to talk about why the engine may not start when the starter turns well.
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The car will not start when the starter is working normally: possible causes
To begin with, at the beginning of the test, you should once again make sure that the starter is working properly. During its operation, when trying to start the engine, there should be no clicks, hum and other extraneous sounds. A serviceable starter should turn the motor with the characteristic hum of the starter electric motor, and do it smoothly, without gaps and failures. If, during attempts to start the internal combustion engine, the indicated signs are noticed, then the malfunction should be looked for in the starter.
After making sure that the starter turns and the engine does not start, it is necessary to proceed to a detailed check of certain vehicle systems. You should start with diagnosing the engine power system, as well as checking the ignition system and some sensors in the electronic control system of the internal combustion engine. In other words, an engine with a working starter often does not start as a result of the fact that no fuel enters the cylinders or the fuel does not ignite for certain reasons.
Checking the fuel system
The reasons for the difficult start of a cold engine. List of faults. What you need to check to diagnose and more accurately determine the problem.
And possible reasons. It's no secret that difficulties of this kind are always an unpleasant and unexpected surprise for any driver. Surely each of us had to witness a situation when the car does not start, the starter turns but does not grasp. Let's try to figure out why this is happening in order to have an idea of how to behave in such a situation. The fact that the starter turns well already means your battery is healthy. Read how to check the condition of the battery.
Not a single car engine is insured against such a situation. It doesn't matter what the outside temperature is. Let us analyze sequentially what to do for different types of power units.
In the case of a carbureted engine, it is a little easier to determine the reasons for the difficult start. First, let's try to pull out the choke knob (air damper control). If that doesn't help, then move on to finding the spark. Poor contact, oxidized or burnt terminals can make it difficult to start the motor. The same goes for poor coil ground contact. If everything is in order with the spark and there is fuel in the gas tank, then there are problems in adjusting the starting device.
The procedure will be as follows:
The injector is distinguished by its own characteristics, which are manifested in case of problems with starting. With these symptoms, you need to start by checking the fuel pump. This may be due to oxidation of the power terminals. After that, it is necessary to check the level of fuel pressure in the fuel rail. Find the side to which the fuel supply is connected. On the side opposite to it, a valve is located under the cap. We click on it and expect that the fuel will run from there. If this does not happen, we begin to check the performance of the fuel pump pressure relief valve and the condition of the fuel filter. 
What could be the reason that I twist the starter, but the injection engine does not start - blog readers often ask me? One of the possible troubles is associated with the flooded. This often happens in frosty weather. It is required to wait until they are dry enough. The engine can be cranked with the starter by first removing the injector connectors.
Diesel
The most difficult to start a diesel engine. The fuel in it ignites according to a slightly different principle. The chambers in which the diesel fuel burns up are heated to very high temperatures, after which the diesel fuel is supplied to them together with air, which is ignited by compression. In cold weather, it is advisable to heat the air in the cylinders with glow plugs. If this is not done, then the car may start, but immediately stalls or works unstably until warming up. 
Even the slightest frost or freezing temperature can be enough for starting problems. In a diesel engine, start by checking the condition of the glow plugs. We start by checking the glow plug control unit. For this we need a control lamp. We connect it to the mass and power of the candles, and then turn the key in the ignition lock. In the case of a working unit, the indicator of the control lamp will light up. 
Other diesel engine starting problems
Another reason why the starter spins for a long time, but the engine fails to start, may be caused by the airing of the high pressure pump. First you need to check if there is power to the kill valve. We turn on the ignition and use the already familiar control lamp for this. When connected, the valve should emit clicks, and their absence may just signal its malfunction.
It remains to check the fuel line - we unscrew either the return line of the injectors, or the plug. If there is an option for manual pumping, it should be carried out until diesel fuel flows and the air stops flowing. If it is not possible to bleed, then it makes sense to check the fuel filter, which is often clogged with paraffin from the fuel or ordinary dirt.
This handbook covers typical malfunctions of most types of passenger cars that can be diagnosed without the use of instruments. It will help you quickly find the cause of the breakdown and start repairing.
It is advisable for a novice diagnostician to add entries from personal experience and the experience of others to the list of characteristic signs and possible causes of malfunctions given in the book - then you will get a solid database of the causes of malfunctions of cars of specific brands and diagnostics will not present problems.
Diagnostics is the basis of repair. It is not for nothing that the most experienced craftsmen are appointed as inspectors in car services, because mistakes in diagnostics and determination of repair volumes lead to financial losses for customers, misunderstanding of orders by mechanics and repeated work. The correct identification of faults is available not only to professional mechanics, it is the result of knowledge combined with a systematic approach. Diagnostics must be continuously learned. Do not rely on a technician, as diagnostic equipment cannot find the cause of a malfunction, it only shows its effect. Start your diagnosis by analyzing the possible causes of the malfunction. Check the condition of the car, find out the client's driving style and how to take care of the car. Find the reason based on the facts.
When diagnosing faults, adhere to the following recommendations:
Apply the method of elimination, go from simple to complex, do not miss the obvious;
Having found out the cause of the malfunction, take measures so that it does not recur;
If the electrical network fails due to a bad connection, check all other connections on the network so that they do not fail too;
If a fuse often blows out, find out the reason, and do not replace it automatically;
Remember that the failure of one part may precede the failure of a more important component or poor system functioning.
Engine
Engine won't start
Non-technical reasons
Condensation on spark plugs after a long idle period of the vehicle without operation.
Moisture on the distributor cap, high voltage wires and their terminals (on a summer morning after a night with temperature extremes, dew or fog).
Drizzle, frost or moisture on the distributor cover, high voltage wires and their terminals (on a winter morning after a night with a temperature drop).
Water on the distributor cap, high voltage wires and their terminals after overcoming deep puddles or fords.
There is a plug in the exhaust pipe (clogged with earth after a reverse maneuver in a hole, ditch, or something else) or moisture (if the car is in deep water).
The gear is engaged instead of the "neutral" position.
The driver forgot to turn off his own blocking of fuel or current.
The reason is in the electrical system
Fuse blown.
Poor ground wire from engine to body.
Start circuit wires are open or loose.
Battery terminals are loose or corroded.
The battery is discharged or damaged (the headlights and wipers will not work).
Defective anti-theft system (or other system) included in the ignition circuit.
Starter gear is stuck in the flywheel ring.
The starter traction relay is damaged.
The reason is in the ignition system
Incorrect ignition timing.
The ignition switch is defective.
Defective ignition coil.
System connections are broken.
Candles are oily or filled with fuel.
Incorrect spark plug electrode gap.
The candles are carbonized.
There are cracks in the spark plug insulators.
No high voltage is supplied to the spark plugs - the tips of the high voltage wires are loose or oxidized, the wires are very dirty or their insulation is damaged.
The order of connecting high voltage wires to the contacts of the ignition distributor cover is violated.
The contacts are stuck and do not open - the gap between the breaker contacts is broken, the textolite pad or bushing of the breaker lever is worn out.
No current flows through the breaker contacts - the contacts are oxidized or burnt, an excessively large gap between the contacts or a weakening of the hold-down spring.
Parts of the ignition distributor are defective.
The distributor is loosely fixed - the ignition moment is lost.
Capacitor broken (short circuit).
Wear, damage to the contact coal or its hanging in the cover of the ignition distributor sensor.
Leakage of current through cracks or burnout in the ignition distributor cover, through carbon deposits or moisture on the inner surface of the cover, through cracks or burnouts in the ignition distributor rotor.
Open in the primary winding of the ignition coil.
Open or short to ground in the secondary winding of the ignition coil.
Broken wires between the ignition distributor sensor and the switch.
Broken wires connecting the switch to the switch or ignition coil.
The switch is defective.
Proximity sensor defective.
Burnout of the resistor in the rotor of the ignition distributor.
Broken wire connecting the power relay to the ignition module. Defective power relay.
Defective ignition module.
The controller is faulty - does not send pulses to the ignition module.
The crankshaft position sensor is faulty, its installation is broken, or the wire connecting the sensor to the controller is broken.
Defective solenoid valve.
The reason is in the fuel system
The solenoid valve in the carburetor gas line does not work when the ignition is turned on.
Poor mixture with cold engine - choke not closed.
Poor mixture - air leaks, in addition to the carburetor diffuser.
Rich mixture with hot engine - air damper closed.
Excess gasoline in the intake manifold - pumping over by sharp pressing on the gas pedal.
Empty fuel tank.
Fuel does not reach carburetor or injection nozzles - fuel filter, pipes or tank vent are clogged.
Defective fuel pump.
Water in fuel.
Steam locks in the fuel line in hot weather.
The air filter is heavily soiled.
Too high fuel level in the carburetor - over-enrichment of the mixture.
Air damper stuck.
The carburetor is out of alignment.
Dirty carburetor nozzles or injection nozzles. Defective gasoline vapor recovery system.
The reason is in the gas distribution system
The timing belt (or chain) is worn out - the phases are out of order.
The key for attaching the gear to the camshaft is cut off - the phases are knocked down.
Valve clearances incorrectly adjusted.
The engine "does not catch" when starting cranking
Unsatisfactory condition of the power supply circuits and control of the ignition coils.
Unsatisfactory condition of the crankshaft position sensor wiring harness circuits and serviceability of the sensor itself.
Engine catches but does not start
Possibility of erroneous polarity reversal of the harness wires to the crankshaft position sensor.
Incorrect mounting clearance between sensor end and timing gear.
Many drivers have been convinced of the capricious nature of the starter when starting the car engine. The car does not start, does not turn the starter, due to the fact that he does not want to scroll. But it also happens the other way around, the starter turns, but the car does not start. When such an unpleasant situation arises, many despair, but this is not worth doing. The vehicle must be towed to the nearest car service or garage box. After that, you should start checking the relevant vehicle systems. At the same time, if a similar situation has arisen, when the starter does not grab, you should pay attention to the nodes that are responsible for the engine's performance.
Check, possible causes of malfunction
Having delivered your car to a nearby service center or garage, it is necessary to inspect the car at the same hour and try to identify possible malfunctions in its systems that are responsible for starting the vehicle. The car does not start, immediately check the starter does not grab.
The initial inspection, when the car does not start, should undergo the fuel system. First, they check the fuel pump, and then look at its components: injection systems (nozzles or carburetor). It is the fuel pump that is the most difficult element of the system. It is necessary to adjust the fuel supply to the engine, without which it will not be able to start.
Diagnostics of the pump, if the car does not start, is carried out by sound when the engine is turned on, which allows you to determine third-party noises during its operation. In the absence of characteristic sounds notifying about its operation, this is a sign of why the engine does not start.
If the car does not start, then the malfunction is eliminated in two ways. The first is to change the fuel pump fuse, which is done first. If nothing has changed, then the situation is much more deplorable - the fuel pump itself "flew". Therefore, a complete replacement of this part will be required.
In the next step, if the car does not start, the fuel filter is checked. Perhaps the start-up does not occur due to contamination in it. If the filter is clogged, then the gasoline does not reach the engine, as in the situation with the pump. The problem is quite trivial, because of the savings in money, many are forced to refuel with low-quality fuel at small gas stations that do not particularly value their image, selling bad gasoline or diesel fuel. At gas stations belonging to more well-known chains with a name, they do not dilute fuel, but also sell it at a higher price than at other points. As a result, drivers are forced to fill in low quality fuel, which clogs the filter, and then does not turn the starter.
Before entering the engine, the fuel goes through three stages of various purification, which few people know. There is also air filtration in the system, the components of which can also become clogged. The solution is to simply replace the filter parts.
At the third stage, when the car does not start, diagnostics are carried out on parts of the ignition system. Initially, you should pay attention to the ignition coil. It is entrusted with the task of creating the necessary voltage, which is used to ignite the fuel mixture in the combustion chamber. If there are no problems, but still does not turn the starter, then we consider the candles. There should be no excess fuel on them, and a spark should also appear. If there is no spark after igniting or replacing the spark plugs, install a new ignition module. Such a solution is necessary for injection internal combustion engines, and on a carburetor engine, the ignition coil changes.
It is also necessary to check the distributor cover if the starter does not turn. It should be without obvious signs of mechanical damage, and a spring-loaded graphite rod will be located inside the assembly.
Other causes of malfunction
After diagnosing all of the above, elements of the fuel system and not fixing the malfunction, and does not turn the starter as before, you should not lose heart, there are a number of reasons why the engine refuses to start. This could be due to the throttle valve. It often burns, so it cannot completely open (close), which is very similar to a breakdown in filters. But unlike their replacement, the flap needs to be cleaned. Having freed it from soot, most likely, it will turn out to start the car. You should also check the battery and terminals.
The problem when the car does not start can be caused by a low battery level or oxidation of the terminals. To identify such a malfunction, you do not need to go through the engine, but you just need to turn the ignition key and if the engine does not start, that is, it does not turn the starter, then the problem is most likely in the power supply system. In this situation, there can be two problems. The first is a discharged battery; to get out of the situation, you need to charge or use the battery of another car to start. If the problem is in the terminals, then you need to install new ones.
Also, if the car does not start, it may be due to violations in the car's wiring. Its diagnosis should be started only after checking all other mechanisms and systems before that, if they are fully operational. Initially, the absence of breaks and the integrity of the upper insulating layer of the wires are checked. Having established that the wiring is unborn, you can diagnose the main devices associated with the car's electrical system.
The most common problem is oxidation of fuse and relay contacts.
It doesn't take long to check the working status of the relay. Using the controller, we will establish the presence of voltage at the positive contacts. If a lack of power is found, then the legs should be cleaned.
This problem indicates the likelihood of a malfunction in the gas pump, which does not allow the engine to start.
A similar weak link can be a relay in the assembly of instruments and wires. If there is corrosion on the contacts, no voltage is transmitted to the device. This prevents it from functioning. Although the trouble is eliminated simply - by removing oxidation or rust. After cleaning, the connecting points should be treated with a special anti-corrosion liquid.
Summing up
There are moments when the starter does not turn, that is, it scrolls to idle, not allowing the power unit to start. All this happens due to some reasons, which are discussed in detail in the publication. Checking the elements of the systems responsible for planting the machine should be carried out only in a situation when the starter scrolls smoothly without jerking, otherwise, with uneven scrolling, the starter mechanism itself should be replaced. Since he is the original source of the problem. Most likely, if the starter does not grasp, then the problem is associated with increased wear of the brushes, therefore, a similar torque occurs with jerks.
Usually, these spare parts for a car are changed without much difficulty, and the engine works fine, but most car enthusiasts do not realize this, as a result of which they buy a new starter mechanism.
Often there is a situation when you turn the key, the starter turns the crankshaft confidently, but the car cannot be started. Some run the engine until the battery runs out, hoping in vain that they might grab it. In fact, after two or three unsuccessful attempts, you should start troubleshooting.
1 The engine does not start when the starter is running - possible damage
When the starter turns, and the engine does not start, it is difficult to find the cause right away. It is required to search for faults in quite a few places. Let's start with the starter. Turn the key again and listen to the sounds it makes. It should give off the characteristic smooth hum of an electric motor without interruptions and nothing else. If you hear clicks, hum and extraneous sounds, we are looking for a problem in the starter. In good condition, the engine most often does not start, because no fuel comes in or it does not ignite.
If the fuel is supplied, the ignition is in order, the starter turns, but the engine does not start, we look for the reason in the electrical equipment: we check individual sections of the electrical circuit and its elements. The reasons can be as simple as possible: a fuse has blown, there is no contact due to breakage or oxidation. Rarely, but there are breakdowns of the electronic control unit. Sensors may break, which send erroneous signals to the ECU, and the ECU incorrectly adjusts the ratio of fuel and air, its supply to the engine.
It is possible that the engine shakes violently during cranking, it seems to start, but does not grab. The reason may be electromagnetic interference, which prevents the sensors from correctly processing the data and sending a signal to the ECU. The induction can be created by the electromagnetic field of the starter. If the crankshaft position sensor (CMP) malfunctions are present, the engine will fail to start. In this case, the fuel is supplied normally, the crankshaft scrolls well with the starter.
Starting faults, when the starter confidently turns the crankshaft, are quite common and do not depend on the type of engine.
2 Diesel - the specifics of troubleshooting
Fuel ignition in a gasoline and diesel engine is fundamentally different. The compression stroke in a diesel engine occurs without fuel, it is injected at the very end of it, when the temperature in the cylinder reaches 700 °. Fuel ignites on contact with hot air. Excess heat from the head is removed by the cooling system. To maintain the temperature inside the combustion chamber, the temperature required to ignite the fuel, the cold engine is heated by glow plugs before starting.
If a cold diesel engine does not start, we start the search for the problem with the spark plugs. The starter can turn for a very long time, but with faulty spark plugs, even at + 5 °, it is difficult to start the engine, not to mention the frost. First, we check the health of the control unit. We connect the light bulb to the candle bus and the mass, turn the key. If the unit is working properly, the lamp will light up. Then we turn the key to its original position, turn off the power bus and check the glow plugs. We connect one contact of the 21 W bulb to the candle, the other to the plus of the battery. If the candle is in good working order, the light is on brightly.
The diesel engine will not start in any weather if the fuel pump is blown or the shutdown valve is faulty. We check with a light to see if the valve is powered. If it is, remove and put on the wire leading to it. A working muffler valve makes clicks. If the valve is in order, air remains in the fuel system. We unscrew the return line of the nozzles or the plug through which we will bleed the air. If there is a manual pumping of the fuel pump, we apply voltage to the valve to open it, and pump diesel fuel until it flows instead of air. If the low pressure pump is electrically driven, turn it on.
In case of failure, when it is not possible to pump diesel fuel, we check the fuel filter: it may have been walled up by dirt or paraffin.
3 Gasoline engine - check the fuel supply
The engine does not start if there are defects in the fuel system: no gasoline is supplied, the starting device is faulty. To check the fuel system of a carburetor engine, we carry out the following operations:
- We sharply open the carburetor throttle valves, observing the gasoline injection (the air filter cover has been removed in advance). If fuel is atomized, it is fed to the carburetor.
- If fuel is supplied, but it is impossible to start a cold engine, check the starting device. We close the air damper - it should completely cover the primary chamber, and the throttle damper should open slightly by 0.8 mm. You will need to remove the carburetor to test the throttle valve.
- When gasoline is not supplied by the accelerator pump, it is not in the carburetor. We upload it manually, start the engine.
- We check the operation of the fuel pump: remove the hose from the outlet fitting and swing it. After a few strokes, gasoline should spray.
- If it was not possible to pump up gasoline, we check the fuel filter, the mesh in the carburetor sump. We change the dirty filter, rinse the mesh.
- Still not supplying fuel? We disassemble the fuel pump and check the diaphragms. If they are broken, the gasoline does not go into the carburetor, but into the sump, diluting the oil.
The oil must be changed, no flushing is needed. We change the diaphragms, pump up gasoline and start the engine.
On vehicles with an injector, the engine will not start if the electric fuel pump is not running. Its serviceability is determined by buzzing after turning on the ignition. Sometimes the reason is oxidized terminals or a fuse, but it happens that the pump burns out. Also, there may be no or insufficient pressure in the rail if gasoline got there. On the opposite side from the gas line connected to it, there is a valve under the cap. We press it - gasoline should spray from there. If this does not happen, we check the fuel filter, intake mesh, fuel pump pressure reducing valve (located in the gas tank).
4 Ignition - how to find and fix a breakdown
If the malfunctions with the fuel supply have been eliminated, and the car does not start, we begin to check the ignition. We unscrew the candles and check the formation of a spark. We put a wire from the distributor cover on the candle, touch the metal on the car with the skirt, and at this time the assistant turns the engine with a starter. A good spark plug will show a strong blue spark. For an injection engine, the absence of a spark indicates a malfunction of the module, for a carburetor engine, the coil.
The injector module cannot be checked at home, but the coil can be checked. Older models have one cylindrical coil, modern ones have a double or monolithic module. The most advanced short circuits, which are installed on each cylinder directly on the spark plugs without wires. The wire coils are checked simply: we take out the central wire from the distributor, bring it to the metal of the car at a distance of 5 mm and turn on the starter. The presence of a spark indicates serviceability.
Often the distributor fails in the car - the burning of the contacts of the breaker-distributor does not allow the engine to start. If the distributor is non-contact, the Hall sensor may have broken. This is not a typical malfunction - sensors rarely fail. Among the most common distributor malfunctions:
- resistance burned out on the runner;
- the distributor cover burnt out;
- Hall sensor wires are cut;
- runout of the distributor shaft through worn bearings.
We check the distributor cover by replacing: the car of experienced drivers is always equipped with a spare one. Non-contact ignition with a distributor has a switch that is responsible for stable sparking. A defective switch can prevent the engine from starting. We detect the malfunction by hand - the broken switch gets very hot.
In vehicles with an electronic system, various sensors most often fail. The malfunction is fixed, and an error message appears on the dashboard, each of which is assigned a code. Ignition failures are often due to wiring when power is not being supplied. In some ECU malfunctions, the engine cannot be started. We repair the unit in a car service or replace it with a serviceable one.
