Why a Diesel Engine will not Start?

The indicator on the dashboard in a modern diesel car, is basically a picture of a coil with few turns indicates that engine is going to start. It is displayed when the glow plugs are turned on and goes off when the computer reports the engine is about to start.

A diesel engine takes pickup depending on the air in the combustion chamber, which is being heated to a temperature high enough to ignite the fuel from the time being it is injected. As they start running, heat is produced by compression of the air in the cylinder with the rise in piston during the compression stroke of the cycle, which is added to the overall warmth of the engine. But when the engine is in cold state, most of the diesel need some help for ignition of the fuel.

The Two Technique Used While in Cold Weather to Ignite The Fuel in Diesel Engine:

  1. First is the heating of combustion chamber by a small electrical heater (often called a glow plug) before starting.
  2. Second is, we can easily add ignited fuel (such as ether) to the air being drawn into the cylinder as the starter is operated.


Starting problem is not a big deal now a day unless there is a technical problem in the car.

Now the diesel cars are as good as petrol cars and for starting assistance there are glow plugs provided in the car. However, if a new car is not well maintained or your car is old enough then there can be an issue in starting of the car, especially on rainy days. Because of wear and tear in old cars, the engine will not be able to generate enough compression in cold climates to start the car instantly, but it got tougher to start a car if there is a technical problem in a car. Also, the injectors got affected due to fuel quality and which can affect the fuel pump as well. While in case of petrol the fuel is much cleaner and generally less adulterated. Also, the fuel injection system works on lesser pressures as compared to a diesel engine and they also need comparatively less maintenance.

Factors that raise No Start Issue

There is a various reason which is responsible for no start of an engine. Here are the few factors that may be responsible for no start problem. However, diesel engines are extremely reliable.

Let’s have a look at these factors:

  1. Fuel – Fuel is delivered at a very high pressure in the diesel engine, so the design of fuel pump depends on non-compressibility of liquid fuel. Air is compressed so eminently in fuel pump so that there is the condition of zero air. Even a small amount of air in fuel pump may cause starting issue. So we hear a somewhat extended cranking in order to purge these air automatically, which is again done by diesel engine itself. So in order to escape these air, there is a small hand pump near to injection pump that must be pumped while loosening the flare nut on each individual of the injector nozzles.
  2. Battery – Because of weak and flat battery engine start running slow. When there is a complete breakdown of battery then no starter will operate, also there is no sound from the engine, lights and windscreen wipers also does not work.
  3. Wrong Fuel – Be careful of the fuel injected. If instead of diesel tank is filled with gasoline/petrol, then the engine will immediately stop working as wrong fuel is injected. A diesel engine shows zero tolerance to gasoline. If by mistake any of the wrong fuel is injected, then the engine stop working and car suffer from a breakdown. In that, we have to go through complete draining of the tank and then refill correct fuel. Also, we have to purge the gas from the lines and fuel injection system.
  4. Contaminated Fuel – It may cause starting issue in a car as any of the contaminated fuel injected in the car. In that case, too for a proper functioning of an engine, we need to drain out the tank completely and then refill with proper fuel.
  5. Weather – Few people believe that weather affects fuel activity. Somewhere the extreme cold or summer fall also affect the diesel fuel. Why this happens. In such cases no practical mechanical intervention will help out, instead, we have to dump out the fuel filters and have to fill with warm fuel which might speed the process slightly and can also eliminate the condensed water that may have accumulated inside the filter, which also becomes a big problem sometimes.
  6. Component Malfunction – In a modern diesel, troubles are more often seen in an engine during running rather than during starting. This is because either engine goes into the Limp home mode or it shoes sudden loss of power. And this happens all because of a partial failure of injectors.
  7. Suction Pump – Because of these pumps, there may be an issue of air getting in fuel lines and causing late start. To avoid such situation primary pump is provided with the suction pump. And these pumps are pressed repeatedly until the lines are full of fuel. And as the lines get full the actual pump of a car will start working normally. Hence car run start immediately.
  8. Glow Plugs – Helpful is starting the car when it is cold weather. Glow plugs look like a Pen. Its tip glow like a car’s cigarette lighter and this glowing end give extra heat to each cylinder, hence the fuel ignites and pushes the engine to start up. And as the engine start running, glow plugs go back to idle state. And all this will be confirmed on a dashboard of a car where the symbol illuminates as the ignition goes on, and goes out as they complete the work of heating the cylinders and confirms the engine is ready to start-ups.

All the above are responsible for not starting the diesel engine. All these may cause the situation where the car won’t start and also not even cranking or car won’t start, but it is cranking in which case engine needs to be a jumpstart.

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