Several factors with regards to fuel control must be working in harmony in order to successfully run an engine. These include: enough compression for heating the mixture of air and fuel; enough spark; and a correct air-to-fuel ratio.
Having too much fuel without enough air within the combustion chamber will cause the engine to either fail to start or run poorly. Maintaining the proper fuel-to-air ratio is usually the function of the computer-controlled F.I. or fuel injection system. This does not apply to older models which use carburetors to mechanically control the fuel-to-air ratio. Failure in maintaining a proper ratio may be due to many causes, including lean mixtures, rich mixtures and contaminated fuel. If the engine does not start, try to see if these could be the causes.
The ideal fuel-to-air ratio is one gram fuel to 14.7 grams air. This will result in an efficient engine. Insufficient fuel or excessive air within the combustion engine may be the cause of a lean fuel mixture, while a rich mixture is one where there is either an excessive amount of fuel or insufficient amount of air. Both lean and rich mixtures cause excessive emission of exhaust fumes. Fuel may also been contaminated with water, rendering it incapable of combustion.
The most common cause of lean fuel mixture is insufficient fuel. Make sure that the fuel tank is not empty! Also, failure of the fuel injectors or fuel pump to work properly also prevents the fuel from entering the combustion chamber. When the fuel injectors fail, fuel does not enter the intake manifold. They may get stuck or fail to get the needed electrical signal to start working. Using a lab scope will determine if there is no signal going to the fuel injectors.
Excessive air is another cause. Leaks in the air ducts or intake manifold put too much air in the cylinders, which bypasses the engine’s Powertrain Control Module. They also bypass the Mass Air flow Sensor and the Vane Air flow Sensor. Air leaks can be checked with the use of a smoke machine.
The fuel supply system delivers the fuel to the fuel injectors. They are responsible for delivering it at the right pressure and volume. This system is comprised of the fuel pump, gas tank, fuel lines, and fuel pressure regulator. These are all susceptible to malfunction. The supply line may also be restricted by a contaminated or plugged fuel filter. The functionality of the fuel supply system can be checked using a pressure-volume test.
A rich fuel-to-air ratio may be caused by a plugged air filter, leaking fuel pressure regulator, leaking fuel injectors, abnormally high fuel pressure, or a malfunctioning fuel control sensor. In older vehicles, excessive oil may also be present in the housing of the air filter, which is also a cause of plugging. It is easy to check the air filter and replace it when needed; however, it is also important to determine there is oil in the filter housing.
Defective pressure regulators need to be replaced, but defective fuel injectors may be too expensive. They can be replaced, but they can also be repaired by competent technicians. Fuel pressure testing can determine if injectors have leaks. It is also important to determine if the computer sensors are working properly; otherwise, they will not respond accordingly.
Enrique Freyre is a leader in industrial machinery, with fuel control as part of their expertise. They provide fuel filters for improving the quality of fuel by removing solids and water from fuel. They also supply equipment for cleaning a vehicle’s fuel consumption tank without removing the tank, which results in considerable time saving. Feel free to inquire about the different issues affecting fuel control and the best ways to correct them. Contact Enrique Freyre for a quote and expect friendly and efficient service.