Often, problems with starting the engine begin in the autumn-winter season. Then, due to the thickened oil, it is difficult for the starter to turn the crankshaft, and the air-fuel mixture cannot ignite in time in cold chambers. But today we will talk about another case. In practice, any car owner has had situations when the engine did not start when the engine was well warmed up.
It won’t start when hot – a popular problem among both VAZ and foreign car owners. Well, let's try to figure it out.
Carburetor engines
In the case of carburetor engines, there are few reasons for this behavior of the engine, and the symptoms themselves are extremely simple. But they may not be clear to most car owners. Most often, such problems only occur in very hot weather. So, the carburetor does not start when hot. What is the reason? Since carburetors are not equipped with an independent cooling system, they cannot be called reliable. When the engine stops working, this unit becomes seriously hot from the hot engine. The fuel that was in the float chamber evaporates under the influence of temperatures. As a result, air pockets form. To solve this problem, press the accelerator pedal one or more times - this approach will help remove air.
The second reason why a carburetor power unit does not start when hot is flooded spark plugs. This happens due to the engine's reluctance to start. Every time the starter rotates, a fuel-air mixture enters the combustion chamber. For a launch it is very rich. If the engine fails to start two or three times, this will be enough for the spark plugs to flood and stop sparking. To start the engine, car enthusiasts press the accelerator several times. But as a result, the already rich mixture is enriched even more. To solve the problem, you need to fully depress the gas pedal and turn the starter. Then the combustion chambers will ventilate and the engine will start.
When starting the engine, you have to turn the starter for a long time. What is the reason?
Main reasons
- Worn brushes in the starter. The malfunction is typical for used cars. You will need to remove the starter cover and replace the two brushes;
- Debris accumulation in the fuel tank. Garbage gets into the tank along with gasoline. These unwanted particles enter the fine filter and clog it. Accordingly, less fuel enters the combustion chamber, which is why you have to turn the starter longer.
- The air filter is clogged. Over time, the air filter can also become clogged. This leads to a lack of clean air for fuel.
- Vehicle age. Over time, compression in the cylinders may decrease. Due to low compression, gases leak into the crankcase and the engine cannot be started. This cannot be done without removing and overhauling the engine.
- Old spark plugs.
Is it possible to crank the starter for a long time?
Yes, you can do this, but be prepared for the following problems:
- Dead battery. Each unsuccessful attempt to start reduces the battery charge. In order for the battery to recover the expended energy, you need to start the car and let it run for a while. But if you can’t start, then soon the battery will simply run out. Then you will need to charge it, ask for a light, or try to start it with a pusher.
- Starter failure. Excessive operation of the starter leads to overheating. And this has a very bad effect on its details. Very often they break down, and then you can’t start the car at all. The bendix, which engages with the crankshaft, also suffers. If it fails to start, the splines or bearing may be damaged. So if you turn the starter for a long time, get ready to replace it.
The starter spins for a long time on a carburetor engine.
You can check a carburetor engine using spark plugs. To do this, unscrew them and examine the deposits on the electrodes.
- red color will indicate low-quality fuel. Most likely, it has a high metal content;
- light or black soot appears when the fuel mixture is too lean or rich;
- a slightly brown tint indicates normal engine operation.
The starter spins for a long time on an injection engine
A typical problem with an injection engine, due to which it takes a long time to crank the starter to start the engine, is an error in the on-board computer. This problem can be solved in two ways:
- By reflashing the on-board computer at a service center (or resetting errors);
- Resetting the on-board computer memory by disconnecting the battery. It is necessary to remove the wire from the negative terminal of the battery for 15-20 minutes so that errors are automatically deleted from the memory of the on-board computer, if they were recorded in it.
Injection cars
The carburetor is a more primitive device, and the reasons for its problems are simple. And you have to tinker with the injection power system much longer. There are other reasons here. If the injector does not start when hot, there are many reasons for this.
Experts first recommend checking the operation of the coolant temperature sensor. Due to a malfunction, it sends incorrect data to the ECU. This disrupts the fuel supply algorithms. Accordingly, the mixture becomes poorer.
Next, another popular place is the injectors. Often, due to defective injection, the engine will not start or starts with difficulty. To check the injectors, they are dismantled and then tested on a specialized stand.
It is also possible that the membrane in the fuel supply control system may be damaged. Fuel is supplied directly to the intake manifold. Due to this, the mixture is enriched. And this is not always good. The fact is that overly enriched fuel does not ignite well from a spark.
But that's not all. If the engine does not start when hot, and the DTS and injectors are in perfect order, it is worth conducting a more in-depth diagnosis. You need to start with the check valve on the fuel pump - if the valve fails, the pump will pump gasoline in the opposite direction. And after the engine stops, it will not be in the fuel lines until the next start.
Typical problem - ignition switch
The lock is very often to blame for poor starting. To diagnose it, check the contact group of the lock.
Sometimes car enthusiasts install a second relay to reduce losses in the lock circuit.
The solenoid relay on the starter may not work. The problem can be detected by ear. There will be no distinct click when turning the key. The relay can be easily replaced. Next, you should check the condition of the wire of the terminal of this relay, and also make sure that the wire that connects the starter and the battery is intact.
Mass air flow sensor - mass air flow sensor
This sensor can cause problems when starting the engine. This element does not like negative environmental influences - it fails quite often. When the engine does not start at all when hot or starting is difficult, then the first thing to do is check this unit.
Failure of the mass air flow sensor is also indicated by failures when pressing the gas, weak traction at certain moments. The power drops or, on the contrary, increases sharply. The starting process is very difficult - the engine choke. Explosions can be heard inside the exhaust system. Engine speed is unstable. The combustible mixture must be prepared with a special ratio of air and gasoline. This proportion is formed by the mass air flow sensor.
Possible faults
The wind cools the carburetor when the car is running; the air-fuel mixture does not form when the engine is turned off. A hot unit increases the temperature of the carburetor, gasoline slowly evaporates, the air filter becomes clogged, fuel lines, fluid passages become clogged, the amount of gasoline decreases and starting the car becomes difficult.
Test runs are repeated to remove blockages in the system, sometimes taking up to 30 minutes. Manual pumping of gasoline helps to cope with the problem.
Problems with injection systems:
- The coolant sensor fails and the operation of the automated system becomes difficult.
- Injector malfunctions rarely occur; holes appear, the pressure in the valve decreases, and the circulation of the working fluid becomes difficult.
- The air flow sensor is broken, the gasoline is oversaturated or insufficiently filled with oxygen, the fire is contained.
ECU software failure
If the car does not start when hot, but all sensors, spark plugs and wires have been checked, then it is worth diagnosing other components.
Sometimes it happens that the software in the ECU unit fails. To check, they are connected to the diagnostic connector in the car, and using a laptop and diagnostic programs, they detect faults. All that remains is to eliminate them by flashing them.
Check the brushes
Another reason is worn brushes or starter bushings. When the brushes have more wear than recommended, they can no longer reach the commutator. This may be one of the reasons why it won't start when hot. If the support bushings wear too much, the armature, due to heating, touches the stator, and a short circuit occurs, which can reduce the starter speed. Here, to make a diagnosis, you should ring the anchor using a multimeter. Turn-to-turn short circuits are also checked. The next reason is the wrong set of bushings. When they get hot, they jam. Here you should go through the bushings with a reamer or sand them with sandpaper.
Diesel engines
If the diesel engine does not start when hot, then the fault should be looked for in the fuel injection pump. Most often, the breakdown is simple and trivial - the oil seals and bushings have failed. The problem can be solved by servicing the pump. But the reason for the non-start may also be in the plunger pair - to solve this problem, a major overhaul of the pump is required.
The same problems are observed in the case of a faulty OPTS. To remove the plunger, the fuel injection pump from the rear is cooled, and then attempts are made to start the car. If the car starts, then the plunger pair is to blame.
If the car does not start when hot, the reason may be worn out oil seals, as well as the bushings of the injection pump drive shaft. There is a place under the seal from which the pump sucks air. This does not allow creating the required pressure in the plunger chamber. To treat and improve the situation, replace the oil seals and bushings.
Diesel engines have a temperature sensor that is used in the injector control system. It also affects startup. If it fails, the injection angle will change.
For both injector and diesel engines, problems in the ECU can significantly affect the normal operation of almost all systems in the car. If everything is in order, then perhaps the block is the reason for the non-start.
HBO for cars
A hot engine can also cause a breakdown in the case of an installed gas system. Since driving on gas has recently become profitable, many drivers switched to this type of fuel, however, they did not take into account some of the nuances of the new system. In hot weather, gas expands more, which leads to increased pressure inside the system and often causes damage. This is why it is bad to drive on gas in the heat.
At high temperatures, seals and hoses can fly off, which leads to gas leakage.
The result is an extremely dangerous situation. To avoid this, try not to fill the tank to full gas in the summer, this will reduce the pressure in the system and the risk of breakdown. If a similar problem occurs, it is recommended to let the car cool down and then visit a service station. You should not repair the gas system yourself; the equipment should be adjusted by a specialist.
Gasoline pump
If the VAZ does not start when hot (especially if it is an old car), then, among other things, it may be that the fuel pump is too hot. This device is cooled by pumping cold gasoline from the tank. But when it's hot outside, gasoline can't be cold. As a result, the pump overheats, making starting difficult. In some cases, it is completely impossible to start the engine. This problem can be corrected by applying a wet cloth to the pump body and periodically cooling it with water. They open the hood, place the car in the shade, and allow the engine and all other components to cool normally. You can just wait until the temperature returns to normal. It is also worth remembering that if the pump has already been overheated, then it will no longer work normally.
Fuel quality
If the car does not start well when it is hot, this may not always be due to breakdowns of any elements. Often the cause may be fuel. Poor quality fuel is one of the most popular reasons. But if the fuel is bad, the car will not start normally even when cold.
Gasoline or diesel fuel can sometimes contain additives that are not needed by the engine and are harmful to it. If diesel is frozen, it turns into jelly, and the pump cannot pump such a mass. It happens that the ECU system adjustments go wrong.
How to improve the launch?
It is recommended to keep the fuel-air mixture as lean as possible. At the moment of starting the engine, squeeze the gas to half. Sometimes you need to press the accelerator pedal all the way. But this should be done only once - otherwise the mixture may become over-rich.
If the spark plugs in the engine flood, you will have to unscrew and dry them yourself, using a hairdryer or any other available means.
