Your fuel system delivers the right amount of fuel to your engine at the right moment. When it works well, you never think about it. When it doesn't, you notice it straight away. Here are answers to some of the most common questions drivers ask.
What is the difference between a carburettor and fuel injection?
A carburettor mixes air and petrol mechanically to create a combustible mixture. Fuel injection uses electronically controlled injectors and a high-pressure pump to spray fuel precisely into the intake or directly into the cylinder.
Fuel injection delivers more power and efficiency than a carburettor, which is why almost all modern cars use it. It also gives much more precise control over engine speed, fuel mixture and emissions.
Fuel injectors vs fuel pumps
Fuel injectors and fuel pumps work together. The fuel pump moves fuel from the tank and builds pressure. The injectors then meter and spray exactly the right amount of fuel into the engine.
- A weak or failing pump causes low fuel pressure, hard starting and loss of power.
- Dirty or clogged injectors cause rough idle, misfires and higher fuel consumption.
Most common fuel system problems
- Clogged fuel filter: restricts fuel flow and starves the engine under load.
- Failing fuel pump: hard starting, stalling or loss of power at high speed.
- Dirty injectors: rough idle, hesitation and poor fuel economy.
- Leaks: a fuel smell around the car is a safety issue and needs checking straight away.
- Clogged air filter: upsets the air-fuel mixture and reduces performance.
What does the check engine light mean?
When the check engine light comes on, the engine computer has stored a diagnostic trouble code (DTC). Common fuel-related causes include the evaporative emissions system, oxygen sensors and fuel trim faults. A mechanic can read the code with a diagnostic scanner. Typical symptoms that point to the fuel system are:
- Rough idle
- Stalling
- Loss of power
- Hesitation when accelerating
- Smoke from the exhaust
What about higher compression ratios?
Higher compression ratios squeeze the air-fuel mixture more tightly before ignition, which extracts more energy from each drop of fuel.
The pros:
- More power from a smaller engine
- Better fuel efficiency
- Stronger acceleration
The cons:
- More heat and pressure inside the engine, which can lead to knocking if the wrong fuel is used
- Higher demands on engine oil, which must protect hotter, more heavily loaded parts
That is why high-compression and turbocharged engines need a high-quality engine oil that meets the manufacturer's specification.
