As we increase the tuning potential of the engine, the fuel system becomes more strained due to the ever increasing need to increase power. By upgrading the various fuel system components it is possible to keep in check the various demands while also ensuring engine reliability, which becomes more of a problem as the engine is upgraded from original specifications.

The fuel system is originally designed with making different constraints and pre-defined criteria in a aid to achieve the following: engine power,fuel efficiency, emissions levels, reliability, drivability under different throttle requirements, maintenance intervals,diagnostic abilities and engine tuning.

We will be covering the following components in this section:

• Fuel Injectors
• Fuel Injector Pump
• Fuel Filter
• Fuel Tank

The fuel injectors are driven by the fuel pump and their job is to spray a fuel and air mixture into the combustion chamber, ready to be ignited to produce power to the driven wheels. The fuel injectors are basically a nozzle, with a valve attached, the nozzle creates a spray of fuel and air droplets (atomisation). This can be viewed similar to that of a perfume dispenser, spraying a fine mist. The valves in the system are controlled by the EFI (electronic fuel injection system) which is governed by the the ECU (electronic computer unit). The whole system uses a multitude of different sensors around the engine to precisely adjust the required air to fuel mixture. This increases engine efficiency compared to older technologies like carburetors, which relied on the air to fuel mixture being sucked into the intake manifold.

The whole fuel system delivers the petrol or diesel from the fuel tanks into the combustion chamber, with a pre defined mixed air to fuel ratio as discussed. As we upgrade other components of the engine,It's ability to remain being efficient at converting this mixture into power also decreases as standard fuel injectors always have a flow rate limit design for their original specifications.

As the needs of the engine increase and power gains are obtained, larger fuel injectors to deliver more fuel flow rates are required once the engine has reached a certain level of tune. Otherwise there is a risk of the engine running lean, which could lead to damage or unreliable characteristic during high throttle load periods.

The fuel pump is used to pump the fuel from the fuel tank, into the fuel injectors, which spray the fuel into the combustion chamber. There are two types, mechanical fuel pumps (used in carburetors) and electronic fuel pumps (used in electronic fuel injection).

Mechanical fuel pumps: these are driven normally by auxiliary belts or chains from the engine.

Electronic fuel pumps: controlled by the electronic fuel injection system, these are normally more reliable and have less reliability issues then their mechanical counterparts.

The fuel filter has the job of making sure no contaminants enter the fuel pump, fuel lines or fuel injectors. Rust, dirt and paint can be present in the fuel tank and will cause premature wear or damage to the vital parts of the fuel system, also can impact the engines efficiency to make power.

By having a fuel filter in place, we eliminate that problem, so it is vital to keep your maintenance schedule up to date. Clogged filters with have a marked effect on performance forcing the engine to run lean.The filter itself is normally a inline cylinder, with a paper filter present and all fuel from the fuel tank is forced to pass through it. There are reusable filters which need cleaning before refitting, or replacement components. Great care needs to be taken when working on the fuel systems.

Unlike the dramatic explosions in the movies, the main aim of the fuel tank is to protect the occupants in the event of a accident from such events. They can be constructed from metal or high density polyethylene plastics and are designed not only to hold large enough volumes of fuel, but resist leakages and vapour escaping from the system.

Normally located at the rear of the vehicle to minimise  the risk of the fuel igniting under front end collisions, the system is closed except access through the filler cap.The system normally will have a gauge sensor located, feeding the information to the driver behind the wheel, also with normally a 30 mile reserve warning light indicating low fuel levels depending on the fuel tank size.