Fuel System

Modern Fuel injection systems need repair technicians who have the correct equipment to diagnose problems and strong skills in hydraulic, electrical and mechanical systems to perform accurate repairs. Call Lucore Automotive Services today to get your car fixed right.

A fuel pump is a frequently (but not always) essential component on a car or other engine powered system. Many engines (older motorcycle engines in particular) do not require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank through a line or hose to the engine. But in non-gravity feed designs, fuel has to be pumped from the fuel tank to the engine and delivered under low pressure to the carburetor or under high pressure to the fuel injection system. Often, carbureted engines use low pressure mechanical pumps that are mounted outside the fuel tank, whereas fuel injected engines often use electric fuel pumps that are mounted inside the fuel tank (and some fuel injected engines have two fuel pumps: one low pressure/high volume supply pump in the tank and one high pressure/low volume pump on or near the engine).
 
In many modern cars the fuel pump is usually electric and located inside the fuel tank. The pump creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. Though electrical components (such as a fuel pump) can spark and ignite fuel vapors, liquid fuel will not explode and therefore submerging the pump in the tank is one of the safest places to put it. In most cars, the fuel pump delivers a constant flow of gasoline to the engine; fuel not used is returned to the tank. This further reduces the chance of the fuel boiling, since it is never kept close to the hot engine for too long.

The ignition switch does not carry the power to the fuel pump; instead, it activates a relay which will handle the higher current load. It is common for the fuel pump relay to become oxidized and cease functioning; this is much more common than the actual fuel pump failing. Modern engines utilize solid-state control which allows the fuel pressure to be controlled via pulse-width modulation of the pump voltage. This increases the life of the pump, allows a smaller and lighter device to be used, and reduces electrical load.
Cars with electronic fuel injection have an electronic control unit (ECU) and this may be programmed with safety logic that will shut the electric fuel pump off, even if the engine is running. In the event of a collision this will prevent fuel leaking from any ruptured fuel line. Additionally, cars may have an inertia switch (usually located underneath the front passenger seat) that is “tripped” in the event of an impact, or a roll-over valve that will shut off the fuel pump in case the car rolls over.
Some ECUs may also be programmed to shut off the fuel pump if they detect low or zero oil pressure, for instance if the engine has suffered a terminal failure (with the subsequent risk of fire in the engine compartment).
The fuel sending unit assembly may be a combination of the electric fuel pump, the filter, the strainer, and the electronic device used to measure the amount of fuel in the tank via a float attached to a sensor which sends data to the dash-mounted fuel gauge.

Fuel Injector Problems
Faulty fuel injectors can cause a variety of problems with a vehicle, including decreased fuel mileage and increased emissions.
Fuel injectors deliver the air-fuel mixture to the engine cylinders in many cars. Problems with these devices can lead to several noticeable decreases in performance and function. Familiarizing yourself with the potential problems and their causes may help you diagnose faulty fuel injectors early and return your car to good working order more quickly.

How Fuel Injectors Work
A fuel injector delivers gasoline to the combustion chamber by using an electrical solenoid valve. When the
car is started, an electrical current is sent to the injector coil. This current causes the coil to form a magnet. The magnet pulls a device known as a pintle from the front of the valve, allowing gasoline to flow through.
When the current is shut off, the magnetic field ceases to exist and the pintle goes back into its resting place and blocks the flow of fuel.

Causes of fuel injector problems
Fuel restriction, regardless of the underlying cause, is the most common reason for reduced performance in a fuel injected system. According to AA1Car.com, an 8 to 10 percent restriction in fuel in just one of a car’s injectors can cause a misfire.
A misfire causes unburned oxygen to force a lean reading in the oxygen sensor. This reading will cause the other injectors to compensate by staying open too long, which will cause too rich of a fuel mixture in the other cylinders. This can be damaging to the engine in some cases.

Heat soak is a common cause of fuel restriction. Heat soak happens when an engine is shut off. The residual heat from the engine evaporates the fuel that remains in the injector, leaving behind waxy compounds known as oilfins. Since the engine is off, nothing will flow through the injectors to wash away the oilfins and they harden and form deposits that restrict the fuel flow through the injector.

Injection system Cleaning
What are the Benefits of cleaning and balancing your injectors? It obviously will depend on the condition of the injectors prior to the cleaning. Older more “clogged” injectors will notice a much larger improvement over injectors that have less accumulation of deposits. No matter the starting condition of the injectors, an increase in performance and fuel economy will pay for the cleaning in a matter of no time. Most high-mileage engines and engines that are used mostly for short trip stop-and-go driving are the most likely prospects for injector cleaning. High performance applications are even more important to maintain and keep in balance. We recommend cleaning the injectors every 25,000 to 30,000 miles to keep them flowing at peak efficiency.

Call Lucore Automotive Services today, to schedule a fuel injection clean and gain better fuel efficiency in your vehicle.
614-873-4470