What causes the generator to consume more fuel?

It is crucial to consider fuel consumption when purchasing a diesel engine generator. Excessive fuel consumption is challenging and not a good experience, and it's a constraint on the pocket and emotions.

The fuel consumption of a diesel generator depends on its age, thermostat, air filter, maintenance culture, and the load it supports. Although, some engines on the same bag can consume fuel differently due to a fault in their water pumps and cooling fans design.

To know precisely and to compare the actual consumption rate of any engine, please consult the manufacturer's manual. With that, you will know if your diesel engine consumption rate is high.

What, then, can influence the high fuel consumption by diesel engine generators?

The following can cause an increase in fuel consumption;

1. AGE.

As a diesel engine generator ages, it may experience several issues that can increase fuel consumption. These can include:

  • Wear and tear on internal components: As an engine age, the internal components, such as the pistons, rings, and valves, can experience wear and tear, reducing efficiency and increasing fuel consumption.

  • Decreased combustion efficiency: An older engine may not burn fuel as efficiently as a newer engine, leading to increased fuel consumption.

  • Increased friction: As an engine ages, the internal components may experience more conflict leading to increased fuel consumption.

  • Increased air leakage: Over time, the seals and gaskets in an engine may become worn or damaged, leading to increased air leakage. It can cause the engine to run, leading to increased fuel consumption.

  • Decreased compression: An older engine may have lreductionssion, leading to reduced efficiency and increased fuel consumption.

Overall, maintaining the engine and keeping it in good condition can help to reduce fuel consumption and extend its lifespan.

Before needing an engine overhaul, diesel-powered generators can operate for at least 10,000 hours and up to 20,000 hours if adequately maintained. Why overhaul? Because parts have a lifespan, most are active in fuel consumption management. 

The injection pump and injector primarily send a regulated amount of fuel to the combustion chambers and one of their faults is high fuel consumption.


The thermostat of a diesel engine generator is a device that regulates the engine's temperature by controlling the flow of coolant through the machine. It is not directly related to fuel consumption. 

But if the thermostat isn't working correctly, it can cause the engine to run at the wrong temperature, impairing performance and efficiency. If the engine is running too cold, it might not be able to reach its ideal operating temperature, which could result in less power and more fuel being used.

On the other hand, if the engine operates at a high temperature, pre-ignition may occur, increasing fuel usage. In either scenario, it's crucial to ensure the thermostat works appropriately to preserve the engine's performance and save fuel usage.


The air filter is in charge of cleaning the air that enters the engine of impurities. The engine may have to work harder and consume more fuel to compensate for the restricted airflow if the air filter is clogged.

The engine may also run lean if the air filter is too dirty or clogged, implying that insufficient fuel is being provided to maintain the proper fuel-to-air ratio. Fuel consumption may rise as the diesel engine attempts to compensate for the low fuel supply as it runs thin.

To ensure; a diesel engine generator's air filter is working correctly and not increasing fuel consumption, it is crucial to inspect and replace it routinely.


There are several ways in which the maintenance culture of a diesel engine generator can contribute to an increase in fuel consumption:

  1. Lack of regular maintenance: Neglecting routine maintenance tasks such as changing the engine oil, air, and fuel filters can reduce engine efficiency, resulting in higher fuel consumption.

  1. Improperly adjusted engine: Incorrectly modified engines can consume more fuel than necessary. For example, if the fuel injection timing is off, the engine may not be able to burn all of the diesel efficiently, leading to increased fuel consumption.

  1. Faulty or worn-out parts: Worn-out or faulty parts such as injectors, fuel pumps, and fuel lines can cause fuel leaks or lead to incomplete combustion, resulting in higher fuel consumption.

Maintaining a diesel engine generator requires regular inspections and maintenance to ensure optimal performance and fuel efficiency.


Increasing the load on a diesel engine generator will typically cause an increase in fuel consumption because the engine has to work harder to produce the additional power required by the load. The fuel consumption of a diesel engine is directly related to the energy it makes, so as the load increases and the engine has to produce more power, it will consume more fuel. Find out more here "What's the relationship between fuel consumption and load on a generator, if any?"

However, we can follow some tips on fuel consumption and save money for a rainy day.

What are some reasons my diesel generator might be consuming more fuel than usual?

Several reasons a diesel generator might be consuming more fuel than usual. Some possible reasons include:

  1. The generator is being used more frequently or for more extended periods.

  1. If you are, using the generator at a higher load, it will lead to an increase in fuel consumption.

  1. The generator is not adequately maintained, which can cause it to run less efficiently and consume more fuel.

  1. The fuel supply may be contaminated or of poor quality, which can cause the generator to run less efficiently and consume more fuel.

  1. The generator's engine may require repair or adjustment, which can cause it to run less efficiently and consume more fuel.

If you are experiencing an unexpected increase in fuel consumption, you can consult a qualified technician to diagnose and address the underlying cause.

How can I prevent diesel engine generators from consuming more fuel than usual?

There are several things you can do to help prevent your diesel generator from consuming more fuel than usual. Here are a few suggestions:

  1. Make sure that your generator is sized correctly for your electrical load. If your generator is too small, it will have to work harder to meet your power needs, which can increase fuel consumption.

  1. Use high-quality fuel. Poor-quality fuel can cause your generator to run less efficiently, increasing fuel consumption.

  1. Keep your generator adequately maintained. Regular maintenance, such as replacing; the air and fuel filters, can help your generator run more efficiently and reduce fuel consumption.

  1. Avoid running your generator at full load for extended periods. Running your generator at full load can increase fuel consumption, so avoid doing this if possible.

  1. Consider using a fuel-efficient generator. Some newer models of diesel generators are more fuel-efficient than older models, so upgrading to one of these may help reduce fuel consumption.

Overall, the key to reducing fuel consumption in a diesel generator is to ensure it is appropriately sized, well-maintained, and running as efficiently as possible. By following these tips, you can help to ensure that your generator uses fuel efficiently and doesn't consume more than it needs. 


Several factors can cause a generator to consume more fuel, including:

  1. The size of the load that the generator is powering

  2. The efficiency of the generator

  3. The age and condition of the generator

  4. The type of fuel that the generator is using

  5. The ambient temperature and humidity

Generally speaking, an enormous load will require the generator to work harder and consume more fuel, as will a less efficient or older generator. Using lower-quality energy or operating the generator in extreme temperatures can also cause it to consume more power. It's essential to carefully consider these factors when using a generator to ensure that it operates as efficiently as possible.


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