Symptoms Of A Failing Fuel Delivery System

The smooth operation of an engine relies on two essential components: - fuel and air. If either of these elements is restricted, the engine's functionality can come to a halt.  The intake system manages the air supply and it is usually a simple process. However, the fuel delivery mechanism can differ greatly from vehicle to vehicle. Any fault in the fuel delivery system can adversely affect the vehicle's performance. In this article, we will explore the types of fuel delivery systems and their failure systems.

In a carburetted engine, the fuel is supplied using a carburettor which mixes incoming air with fuel before it enters the engine. As air flows over a narrow tube known as  the venturi tube, the air flow’s momentum creates a low pressure  area causing the fuel to flow with the air. This fuel-air mixture then enters the engine through the intake manifold for combustion. The fuel supply is regulated in different ways depending on the carburettor design. Carburetors have been used in vehicles since the advent of automobiles. They are simple mechanical fuel delivery devices still found on older vehicles and many modern small-capacity engines like lawn mowers, generators, etc.

In a fuel injection system, the fuel is supplied by an injector either directly into the combustion chamber or through the intake manifold, depending on the type of fuel injection system. The amount of fuel sprayed by the injector is controlled by an ECU which regulates the fuel supply based on the airflow volume, throttle position, engine speed and oxygen sensor readings. This allows precise control of fuel supply making fuel injection very efficient. Fuel injection systems actively work to provide increased performance and efficiency based on driver needs. EFI systems are found on all modern engines today, primarily because of their numerous advantages over carburetors.

Unlike mechanical carburetors, fuel injection is completely electronic and uses sensors to continuously monitor and calculate the exact amount of fuel required to maintain a stoichiometric fuel-air mixture. his electronic control allows for meticulous regulation of fuel supply by the Engine Control Unit (ECU), resulting in a significant enhancement in fuel efficiency. 

In order to get better performance or fuel mileage, the fuel delivery can be easily tuned using the ECU. No physical tweaking is required like in the case of a carburetor. Instead, enhancing performance is as straightforward as introducing a new engine tune to the ECU, thereby capitalizing on the flexibility of electronic control. 

A major benefit of EFI systems is  significantly enhanced engine starting performance in both hot and cold conditions. This improvement stems from the EFI's capability to precisely compute the ideal fuel-air mixture required for engine ignition, a feature that surpasses the capabilities of carbureted systems. 

A fuel injection system can be optimized to deliver fuel in the right amount at the right time for better combustion and atomization which helps improve fuel economy and complete combustion leading to lower emissions. 

Fuel injection systems can increase engine horsepower and torque by providing optimized air-fuel mixture and atomization for cleaner, more efficient combustion which helps increase engine power. 

• Fuel Pump
• Fuel Filter
• Fuel Hose
• Fuel Injectors
• Fuel Tank
  
• Fuel Pressure Regulator
• Various Sensors
• Fuel Rails

Although carburetor and FI systems are quite different in operation, their signs of failure can be pretty similar since they perform the same task. Here are common fuel delivery system failure symptoms:

One of the most common causes of fuel delivery problems is inability to start the car. Insufficient and inadequate fuel supply can lead to compromised engine startup. Clogged fuel injectors or carburetors can restrict fuel supply. A bad fuel pump can prevent fuel from traveling to the engine at all. A dirty fuel filter can also restrict fuel supply. A leak in the fuel lines can be another cause of engine starting problems. Here's how you can troubleshoot car starting problems.

Engine misfires occur when one or more cylinders fail to ignite. This can happen more commonly in direct fuel injection and multi-carb systems since the fuel supply is handled by a single injector or carburetor attached to one or two cylinders. This means the problem lies in that injector or carb. 

If the fuel supply is not consistent especially at lower RPMs, the engine will not idle correctly. You may hear the engine misfire or sputter during idling. This can be caused by a clogged fuel filter, a failing fuel pump or contaminants in the carburetor or fuel injectors. 

A reduced pedal response can be an indication of fuel delivery issues. This can be especially prominent under heavy load conditions like climbing a hill, carrying excess cargo, etc.  The engine might experience fuel deprivation, leading to misfires and erratic operation. If you notice the engine struggles to accelerate during normal conditions, then it is most likely a fuel delivery problem. 

It is common to experience reduced fuel economy when one or more components in the fuel delivery system fail. A broken injector nozzle can spray excessive fuel into the cylinders resulting in poor performance and increased fuel consumption. A leak in the fuel hose can impact fuel consumption considerably. A malfunctioning choke valve in a carb can cause excess fuel draw affecting fuel economy. A bad fuel pressure regulator on a fuel rail system can allow excess fuel pressure which can cause the injectors to spray more fuel than required.