Common Diesel Fuel Questions and Answers

On this page we will answer the most common questions about diesel fuel and system problems.

Q. What is diesel fuel?

A. Diesel fuel is generally the result of a mixture of derived petroleum compounds known as distillates of hydrocarbons,

Sometimes it may have extra additives added when manufactured to improve performance and increase shelf life.

Q, What if I put petrol/ gasoline in my diesel fuel?

A. Well you have a big problem! Adding petrol/ gasoline in a diesel tank can create destruction to the fuel injection system, pump and the engine itself.

A diesel fuel pump operates on very small tolerances at massive pressures and is lubricated and cooled by the diesel fuel. Petrol/ gasoline has no lubricating qualities, remember diesel is an oil aka. Lubricant.

No lubrication = metal particles forming in the fuel system due to excessive friction, this can cause massive wear to the entire fuel system.

Uncontrolled fuel ignition of the petrol under the much higher compression can cause internal engine damage to pistons and internal engine components.

You should not run a diesel engine that has been contaminated with petrol in the tank. Seek professional help to remove the petrol before using it.

Q. What is Alpine diesel?

A. Alpine Diesel is a special blend of fuel that resists freezing. In cold climates, where the temperature gets down to below zero you need to use this type of fuel.

The temperature level when diesel fuel starts to thicken up and form into a wax is known as the cloud point, thick fuel can damage injectors, block filters and stop and engine from operating.

Q. What are the main quality characteristics of diesel fuel?

A. Diesel fuel ought to be clean and water-free. It should flow well during cold weather and should not damage injectors or any other fuel system components.

Fuel should have a level of cetane to supply good characteristics and combustion.

Q. What does diesel fuel cetane mean?

A. The cetane number indicates the fuel’s ignition efficiency that influences not only starting but also combustion burn.

A higher cetane volume does not significantly increase engine performance. Many engine producers prescribe at least a 40 cetane diesel fuels.

Q. What does fuel cleanliness mean?

A. Cleanliness in diesel fuel means complete removal of water and polluted matter in fuel.

This is very important due to low tolerances between injector nozzles and injector pumps. All engine manufacturers equip their fuel systems with filters.

These should be periodically drained and replaced as per the engine manufacturers instructions. Many filter manufacturers like Racor have filters with drain valves which are best suited to marine applications where water in fuel is a common problem.

Q. How can water get into diesel fuel and what does it do?

A. The water contamination can enter as different forms such as condensation, shipment, leakage by inadequate filling pipes, and reckless handling in diesel fuel storage systems.

Water can cause damage of the injectors and pump, bacteria and fungi growth, and plugging of filters with corrosion and biological materials causing all sorts of issues. Therefore, water ingress into fuel must be tested periodically for equipment and storage tanks and drained or cleaned by fuel polishing as needed. Biocides can be appropriate in extreme cases for bacterial growth management.

Q. What is the primary cause of low diesel fuel efficiency?

A. Contamination of fuel by water and dirt from the mishandling of fuel is the leading cause of low diesel engine performance.

It would be ideal if you were extra careful to ensure that fuel tank tops, filling nozzles are kept clean to reduce the chances of contamination. Regular water removal from storage tanks, diesel tanks for cars, and filter bowls are essential. A system with no water contamination can stop fuel problems quite easily.

Q. Why do diesel engines smoke?

A. Incomplete combustion produces diesel fuel smoke, what you see as black smoke is simply fuel that has not been burnt in the combustion chamber.

White smoke is caused by small droplets of unburned fuel owing to the low temperature of the engine. This smoke should fade as the motor engine warms up. Light smoke is caused by defective injectors, inadequate air, and overload, and if the engine is over-fueling. Blue smoke is the result of the combustion of oil, which is a low mechanical quality signal such as a worn-out engine rings, pistons and sleeves.

Q. What does fuel heat quality mean?

A. The heat energy content of diesel fuel is the energy consumption per liter of diesel fuel combustion. Measured in megajoules, it is related to the petroleum hydrocarbon mixture.