Why won't the car start when hot?

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

It is often difficult to start the engine in winter, when the outside temperatures are very, very low. However, it often happens that carburetor engines begin to show their "whims". It happens that the engine does not start when hot. So, if you stop and stand for a few minutes, then you can no longer start the car.

Experienced motorists often know all the features of their car and also know the various ways and methods of starting the engine in a variety of conditions, but the majority, and these are many beginners, with such problems, they torture the starter, battery, and their nerves for a long time, but the car does not respond to this.

Typical causes of difficulty starting a carburetor machine

If the car suddenly does not start hot, then with a skillful approach, the problem can be completely solved.

Here you need to understand that when the engine is running, a huge amount of air passes through the carburetor. As a result, the carburetor cools down. The same effect can be caused by fuel,which also passes through the carburetor. The result of this is that during operation, carburetor temperatures will always be lower than the engine, and certainly lower than the boiling point of gasoline.

However, this situation will continue as long as the motor is running. If the car is stopped, the temperature of the carburetor will begin to rise from a sufficiently hot motor housing. At this point, there is no longer any air flow, so it will not be cooled. Gasoline remaining in the float chamber will evaporate very rapidly as temperatures rise.

Fuel fumes will fill any cavity they can reach. It can be an intake manifold, a carburetor directly, an air filter and other parts. The levels of fuel remaining in the float chamber will drop below their norm, and sometimes so-called gas locks in the fuel system may form.

How long this process will take depends entirely on how the fuel system of a particular car is arranged, on the temperature regime of the engine and on the temperature overboard. Other factors can also affect duration. So, this effect can last from 5 minutes to 30 minutes.

If the driver suddenly wants to start the car during the passage of these processes, then due to the huge volume of fuel vapors that have accumulated in the intake manifold cavities, too rich fuel mixture will enter the cylinders. This is the main reason why the engine does not start on a hot engine.

Reasons for poor starting of injection and diesel engines

If witheverything is very clear with carburetors, but with injectors and diesel units everything is more complicated.

There are many more reasons. This may be due to coolant sensors, air flow sensors, injector problems. Also, it often does not start hot due to breakdowns in the fuel pump, malfunctions in the ignition module.

Injector

So, the car won't start when it's hot. Among the most popular reasons, the coolant temperature sensor is distinguished. If it fails or gives incorrect readings to the computer, then the combustible mixture is supplied incorrectly. This reason is relevant for both diesel and injector.

Next, injectors are isolated that can pass fuel. When they are in a free state, vapors are formed, the mixture is re-enriched. As a result, it does not start on a hot injector. To check the nozzles, you need a stand. But if it is not there, you can check the condition of the candles. To do this, the candle is unscrewed and carefully studied. With a sealed nozzle, the candle will be dry. To solve this problem, you need to change the nozzles. Some try to clean them - this is not a panacea. To start the car with such a malfunction, you need to slightly open the throttle.

This is done in order to purge fuel vapors and relieve pressure in the fuel line. This reason can also occur if the o-rings on the injectors are out of order. Nozzles are one of the most popular reasons if the car does not start onhot.

Diesel Diseases

Diesel engines often fail to start a hot engine due to a broken injection pump. The main symptom of such a breakdown is a worn plunger pair. The same symptoms can be observed if the WAPT valve is faulty. To eliminate any suspicion of a plunger, the back of the high pressure pump is cooled and the car is also tried to start. If the car can be started, then the problem is in the plunger.

Also, the machine will not start when hot if the bushings and oil seals of the high pressure pump drive shaft are worn out.

A space appears under the stuffing box from which air is sucked into the pump. This does not create the necessary pressure in the plunger chamber. In order to cure this, the oil seal and bushings are changed.

Some diesel units do not start using the control nozzle, which has a temperature sensor, which is responsible for creating an air-fuel mixture. If this sensor is broken, then the injection operation is significantly disrupted. This problem is solved by replacing this part.

It is not uncommon that a diesel engine won't start when hot due to an extended pump drive. As with injectors, this changes the fuel injection angle. Only correction can help here. To do this, the pump is simply rotated relative to the body of the device by a few degrees.

Hot motor stops

This is another very embarrassing moment. It is especially typical for the domestic automobile industry of the old years of production. If the enginesuddenly overheated, then it suddenly just stops. This often happens during hot summers.

Among the popular causes is a gas plug in the fuel pump. These plugs do not allow the pump to function normally, and the float chamber is dry. The combustible mixture simply does not get there. In this case, only cooling the pump will help. Water is poured over it.

You should be careful with these devices. The pump housing may contain glass parts.

Glass caps often burst when the temperature drops sharply. If cooling does not solve the problem, then the pump needs either repair or replacement.

Starter and problems with it

Many are faced with the fact that the hot starter does not start. It spins, but does not cope with its task. These problems are very often discussed on specialized forums.

The first thing that comes to mind is a dead battery. However, often after testing it turns out that the battery is completely he althy and normally charged. Here you can look for problems in the starter itself, its power circuit or wiring.

Why the starter does not work well

In the event that it does not start on a hot VAZ, it may be the battery. Often, drivers get out of their vehicles and leave their headlights on. Here the battery can run out very quickly, especially if it is old. Also check the terminals.

Further, the starter may not start the engine due to early ignition. Check the symptom as follows: pull the wire out of its coil and try to twistwarm engine without spark. If the rotation is not hindered by anything, then the ignition should be corrected.

Check brushes

Another reason is worn out 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 does not start when hot. If the support bushings are too worn, then the armature touches the stator due to heating, and a short circuit occurs, which can reduce the starter speed. Here, to make a diagnosis, ring the anchor with a multimeter. Interturn short circuits are also checked. The next reason is the wrong set of bushings. When they heat up, they jam. Here you should go through the bushings with a reamer or process them with sandpaper.

Typical problem - ignition switch

The lock is very often to blame for a bad start. To diagnose it, check the contact group of the lock.

Sometimes motorists mount a second relay to reduce losses in the lock circuit.

The solenoid relay on the starter may not work. The problem can be identified by ear. When turning the key, there will be no distinct click. 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.

Check engine

It happens that sometimes one or more liners are rubbed on the crankshaft.

When the engine is cold, the starter spins it perfectly, when the engine warms up enough, the liner clamps the crankshaft. It also happens that due to wear of the axial displacement liner, the crankshaft itself is displaced from its axis. All these problems can only be fixed by repair.

How to make a hot engine start well

To do this, it is necessary to deplete the fuel mixture to the norm. At the moment of starting a hot engine, the gas pedal is squeezed out to half. Sometimes it even happens that it is necessary to depress the pedal completely. If you press and release the pedal several times, then you can not improve, but, on the contrary, worsen the situation. The pump will send the fuel mixture more and more, the more it will re-enrich the mixture. In this case, starting the engine will be very problematic.

Beginner drivers, having traveled by car, begin to understand it better, and then such problems do not arise. After starting the engine with a few pressures on the accelerator, the car will move off without any problems.

That's about all there is to say about this issue. If it doesn’t start hot, there may be other reasons, but now you know the main sources and will be able to diagnose your car yourself.