Can sugar in the fuel tank ruin the engine?

This blog will answer the following question: Can sugar in the fuel tank ruin the engine? What happens if you get sugar in the fuel tank? What can cause damage to the fuel system of the engine? Can anyone put sugar in your fuel tank?

Can sugar in the fuel tank ruin the engine?

No, sugar in the fuel tank does not ruin the engine. However, it can lead to very expensive repairs as the fuel tank must be removed from the vehicle to clean and remove the sugar. In some cases the fuel filter and low-pressure fuel pump also need replacement.

Putting sugar in the fuel tank to sabotage a car is a very old myth. The idea is that the sugar will dissolve in the fuel and enter the fuel system of the engine. The contaminated fuel is then injected into the combustion chamber where the sugar caramelizes.

This sticky substance can restrict the movement of the piston in the combustion chamber and cause damage to the moving parts of the engine. In reality, the sugar never enters the fuel system of the vehicle.

There are fuel filters in the fuel tank before the low-pressure pump. In diesel vehicles, there is also a larger low-pressure fuel filter before the diesel enters the high-pressure pump. So it is very difficult for sugar to enter the fuel system of the car and ruin the engine.

All the latest cars have direct fuel injection engines, car manufacturers use pre-filters in the fuel system to ensure no dirt enters the high-pressure side of the fuel system and clogs the fuel injector.

What happens if you get sugar in the fuel tank?

If someone puts an excessive quantity of sugar in the fuel tank, the sugar cannot dissolve as it does in the water. Water is polar in nature and it will separate the sugar crystals. Fuel like gasoline or diesel is non-polar in nature. Sugar just settles at the bottom of the fuel tank.

Although the sugar will not dissolve in the fuel tank it can lead to the following problems.

• Incorrect fuel level

When sugar gets in the fuel tank it settles at the bottom and it does not dissolve. The fuel tank level sensors are also present at the bottom of the fuel tank. The float connected to the fuel level sensor reaches the bottom of the tank as the fuel tank becomes empty.

All the fuel tank level sensors use potentiometers that are either connected to the instrument cluster or fuel system control unit. The control unit then calculates the current fuel level based on the resistance from the level sensors.

When the sugar settles on the bottom of the fuel tank it can trap the float and give a false reading of the fuel level. The float can also rest on the deposited sugar and the vehicle will turn off even if the instrument cluster is displaying a fuel level above the empty mark.

The remedy is to remove the fuel tank from the vehicle and clean the tank. Some vehicles have sealed tanks from one side, therefore it is not possible to clean the fuel tank. Such tanks must be replaced.

• Insufficient pressure in the fuel system

The low-pressure fuel pump is installed in a dashpot; a fuel filter is connected at the input of the low-pressure fuel pump. There is also a suction jet fuel pump which is present on the left side of the fuel tank.

The sugar deposit can block the inlet of the low-pressure fuel pump or the suction jet fuel pump. If the suction jet fuel pump is blocked, it cannot transfer the fuel from the left side of the fuel tank to the right side.

The main low-pressure fuel pump will continue to pump only the right side and eventually the pressure on the low-pressure fuel system will drop below 4 bars. The engine will not get sufficient fuel pressure to continue operating at idle engine speed and the vehicle will stall.

What can cause damage to the fuel system of the engine?

Although sugar in the fuel tank cannot damage the fuel system of the engine, the following are some of the reasons the fuel system may be damaged and become inoperative.

• Incorrect fuel

Using incorrect fuel in the vehicle means putting petrol or gasoline in the diesel engine powered vehicle or vice versa. The diesel engine does not have an ignition system, diesel is a self-igniting fuel and when petrol is mixed in the diesel the engine does not start.

Petrol also causes irreparable damage to the high-pressure fuel pump as there are no lubricating properties in the petrol. Diesel engines also operate at 2000 bar fuel pressure, therefore petrol in the fuel rail and injectors can damage the injector nozzles.

Similarly, if diesel is mixed with petrol, components like the high-pressure pump and low-pressure pump can be cleaned. However, fuel injectors are permanently damaged. Petrol engines also use spark plugs to ignite the air-fuel mixture. 

As diesel is injected into the combustion chamber, spark plugs cannot ignite the diesel fuel and the electrodes are damaged.

• Water in the fuel system

If there is water in the diesel as well as petrol engines then the fuel system consisting of the fuel rail, high-pressure lines, low-pressure fuel lines, and fuel pumps must be replaced. It is not possible to clean and remove the water completely in the fuel system especially if the engine was running.

The latest vehicles also have fuel tanks that are sealed from one side. The water from such fuel tanks cannot be drained completely and complete fuel tanks are replaced.

Can anyone put sugar in your fuel tank?

The fuel tank filler neck is protected by a fuel flap and fuel flap recess. It is not possible to put sugar in the fuel tank unless the fuel lap is unlocked from inside the vehicle or the vehicle is left unlocked. 

Even if someone gains access to the fuel filler cap, the fuel filler neck of the fuel tank is not straight. There is a safety flap inside the neck that does not open unless a fuel hose is inserted in it. Therefore, it is not possible to put sugar in the fuel tanks of passenger cars as the fuel tanks are located away from the fuel filling point. 

Commercial vehicles like trucks and buses, on the other hand, are a different story. When the commercial vehicle is refueled the fuel hose is directly inserted into the fuel tank. So it is much easier to put sugar in the fuel tank.

Conclusion 

This blog debunked the myth that it is possible to sabotage a car by putting sugar in the fuel tank. The real reasons that can damage the fuel system and stall the vehicle are also explained. Therefore, it is important to check the owner’s manual and the fuel filler lid and refuel with the correct fuel to avoid expensive repairs.