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How Does My Car’s Fuel System Work?

how a fuel system worksFuel is essential to the engine and is a vital element in the combustion process so that it may convert it to energy to propel your vehicle. It is mixed with air, ignited, and eventually converted to exhaust. If you haven’t noticed, though, with most cars, the fuel tank is towards the back end and the engine is in the front of the vehicle. How does the fuel get to the engine? What happens with the fuel once you’ve filled up the tank? Read on to find out how a car’s fuel system works and how to maintain it so that your car continues to use fuel in the most efficient way possible.

Ideally, when your vehicle’s gas gauge gets down to a quarter tank, you pull into your favorite fueling station and fill up the tank. The gas station pump is where fuel begins its journey: 

  1. From the pump to the tanks the gas travels through the fuel pump. The pump sends fuel from the gas tank to the engine. Some vehicles are equipped with multiple gas tanks and even multiple fuel pumps. Multiple fuel pumps are ideal for ensuring the vehicle always has access to fuel no matter the terrain that the vehicle is traveling on. For example, if a vehicle is making a sharp turn or traveling on a steep incline and gravity forces fuel away from one fuel pump, it guarantees that at least one of the pumps has access to fuel.
  2. The pump forces fuel through the fuel lines that deliver fuel from the tank to the engine for combustion. Fuel lines are made of durable metal, plastic materials and though they are located in the undercarriage of the vehicle, and seemingly in a vulnerable position, they are placed in areas that cannot be damaged due to elements, road conditions, or exposure to heat from the engine’s exhaust or other components. 
  3. The fuel filter is the next stop for gasoline before it reaches your engine. It is imperative that the fuel that enters the engine be uncontaminated and free from dirt or particulates. To prevent any debris from entering the engine, the fuel filter will aid in removing dirt or debris. A clogged or dirty fuel filter is unable to trap harmful particulates from entering your engine and cause all sorts of damage. Newer vehicles may not have serviceable fuel filters as they are located in the fuel tank. Replacing the filter requires replacing the entire set up.
  4. Once passed through the fuel filter, the fuel reaches the engine and is in injected into the combustion chamber to create combustion utilizing fuel injectors. 

Fuel Injection: Past, Present, and Future

In the past, vehicles utilized carburetors to create the right mix of air and fuel for combustion. A carburetor uses the pressure created from suction by the engine to bring in the air. While this accomplishes what the vehicle requires, it wasn’t entirely reliable with fluctuating RPMs. The throttle determines how much air and fuel is required based on the vehicle’s current speed and demand on the engine. With varying RPMs, this results in poorer fuel economy and the carburetor struggle to run smoothly. 

To combat the struggles of carburetors, fuel injection systems were introduced beginning with mechanical fuel injection. While an improvement, as mechanical fuel injection systems were able to gauge the correct amount of fuel required for the engine and deliver it directly via injection, they still required tuning, like carburetors, for best performance. 

Electronic fuel injection is the norm in most vehicles today. It’s a newer and more advanced system controlled by the Electronic Control Unit (ECU), and is ideal for many reasons including improved fuel efficiency and better performance. The fuel pressure regulator maintains a specified amount of fuel pressure, so the injectors, based on calculations from the Mass Air Flow (MAF) sensor, observe how much air enters the engine. This allows the ECU to calculate and determine how much fuel is needed to meet the optimal fuel to air ratio determined by the manufacturer. Electronic fuel injection uses a pressure regulator to maintain an even pressure that draws fuel to the injectors which then spray a mist of fuel into the combustion chamber. Direct fuel injection systems, synonymous with diesel engines, have one injector per cylinder that delivers fuel directly to the combustion chambers.

In the future, the fuel injection process can only improve with better precision to create maximum efficiency and less waste. Some speculate that diesel may be the key to improvement, though, diesel does have its own set of disadvantages, as well.  

Fuel System Maintenance for Your Car

After driving so many miles, the wear on your car can affect its performance. That’s why routine maintenance on your vehicle is so important. Can you imagine if you never changed your oil? Your engine wouldn’t last long. The same can be said for any major component in your vehicle. Having your fuel system serviced regularly can help prevent the inconvenience of a failed fuel pump, ensures optimal fuel efficiency, and the very best performance intended for your vehicle. 

At Sun Devil Auto, we know the fuel system and just what it needs to continue operating for peak performance. Replacing your fuel filter every 60,000 miles as well as a fuel system cleaning every 30,000 miles is one of the best ways to ensure your vehicle continues processing and burning fuel properly. We offer a 4-Step Fuel System Cleaning that will make your car feel “like new” again. Schedule your appointment today for the Sun Devil Auto 4-Step Fuel System Cleaning which includes:

  • Engine De-carbon – Breaks up the varnish in the engine allowing the valves to close completely, attain maximum compression, and improves the atomization of fuel


  • Fuel Injection Service – Enhance spray from a drip to a mist for better use of fuel by cleaning the needle of the injector and removing pooled or puddled fuel collected on the tops of injectors.
  • Throttle Body Service – As carbon builds up in the throttle body, closing the butterfly seal becomes more difficult and thus stays slightly ajar, increasing idle and decreasing fuel economy. Additionally, the buildup is removed from vital sensors, such as the MAF, to enhance performance. 
  • Fuel Additive – Over time, moisture collects in your fuel tank. The additive is meant to remove any moisture as well as continue to clean your fuel injectors as you drive.