Description: The typical air filter is a disposable, pleated-paper element with a sealing gasket made of synthetic material.
Purpose: The air filter traps dirt particles, which can cause damage to engine cylinders, walls, pistons and piston rings. The air filter also plays a role in keeping contaminants off the airflow sensor (some fuel-injected cars) and sometimes in cleaning the air that enters the crankcase for crankcase ventilation. The air filter also serves as a silencer for your car’s intake system. Your car’s engine can use close to 40,000 litres of air for every 3.5 litres of fuel burned, so it’s easy to see how big a job the air filter has.
Maintenance Tips/Suggestions: Although your car’s owner’s manual may specify an inspection interval for the air filter, it’s really best that it be checked at every oil change. Dirty and dusty driving conditions will require more frequent filter replacements, so keep this in mind. Driving with a dirty filter restricts the air entering the engine, and if severe, can impact fuel economy and performance.
Description: The typical fuel filter for most fuel-injected cars consists of a high-pressure canister filled with filtering media. Filters may have clamped, threaded or special fittings to ensure reliable connection to the fuel system.
Purpose: Fuel filters trap harmful contaminants that may cause problems with intricate fuel injectors. Fuel filters clean the fuel whenever the fuel pump runs (unless the fuel injection system is a “returnless” design). Fuel moves continuously up the supply side, through the filter to the fuel rail or throttle body. The fuel that doesn’t make it into the engine returns to the tank and the whole process starts over again. With a full tank of gas, the filter may clean the volume of fuel in the tank many times before it’s all used.
Maintenance Tips/Suggestions: Some carmakers don’t recommend replacing the filter at all during the first 170,000 kilometers of “normal” driving. Since “normal” usually constitutes severe driving because of less than normal conditions, it’s best to replace the filter every two years or 40,000 kilometers. A contaminated filter can restrict fuel flow from your car’s electric fuel pump, eventually taking a toll on its life. Frequent filter replacements remove all doubt about whether the filter may cause other problems down the road.
Most filters on domestic cars and trucks hide underneath on the frame or body. Just the opposite is true on the imports. They usually put their filters somewhere in the engine compartment.
Description: Fuel injection consists of a throttle body to control airflow, the fuel injectors, various engine sensors, an electric fuel pump and a fuel filter. The system is controlled by the car’s powertrain control module (PCM), which makes all decisions for controlling the injection system. Most early fuel injection systems used a throttle-body design, where one or more injectors were mounted on a throttle body, resembling a carburetor. Use of the throttle body system faded away gradually as multi-port fuel injection became more prevalent. Multi-port uses a separate fuel injector for each cylinder, located near each cylinder’s intake valve port. Virtually all engines now use multi-port injection.
Purpose: Fuel injection delivers fuel to the engine in exactly the right amount for all engine-operating conditions. Not only does the system provide better control for fuel economy, performance and emissions, it also does away with many of the maintenance requirements of a carburetor.
Maintenance Tips/Suggestions: On 1996 and newer vehicles, your car’s fuel injection system is integrated with a second-generation onboard diagnostic system, known as OBDII. The PCM stores a Diagnostic Trouble Code (DTC) when it detects a problem in one of the monitored circuits. A professional technician can access this information using a scan tool connected to the vehicle’s Data Link Connector (DLC). Although many DTCs are sensor-related, it does not necessarily indicate a faulty sensor. There may be problems in that sensor’s circuit, or there may be several interrelated problems.
Areas of the country with an emissions testing program are placing added value on OBDII checks, where this technology may be used in place of tailpipe testing. The system also alerts you with a Malfunction Indicator Lamp (MIL), indicating that the system has detected a problem, which could cause excessive emissions. This light is usually labeled SERVICE ENGINE SOON or CHECK ENGINE. If the light appears, you should have its cause investigated by a professional technician at your earliest opportunity. If the light flashes, the condition is more severe and must be checked out immediately to prevent damage to the catalytic converter.
Description: Cars all use electric fuel pumps nowadays because of the universal application of fuel injection and its need for higher pressures. Electric fuel pumps are almost always located inside the gas tank, but there are some applications where the pump may be located along the frame or uni-body channel. The pump has a strainer at its pickup to filter out contaminants and uses an electric motor for power. Fuel is used as a lubricant and coolant for the motor. The electric fuel pump has its own electrical control circuit, typically consisting of wiring, a fuse and a relay. This circuit interacts with the car’s powertrain control module (PCM), which governs and monitors fuel pump operation.
Purpose: The fuel pump provides fuel with the proper pressure and volume for delivery by the fuel injection system. The electric fuel pump circuit also employs various safeties that stop the pump from running in the event of an accident.
Maintenance Tips/Suggestions: With fuel-injected vehicles, regular fuel filter changes can help extend the life of the electric fuel pump. It’s best to replace the filter every two years or 24,000 miles. A contaminated filter can restrict fuel flow from the electric fuel pump, eventually taking a toll on its life.
You can also help protect the pump by keeping the tank at least half-full at all times. Since fuel cools the pump, having plenty of fuel in the tank helps keep the pump from getting too warm, which could damage it.
Another good reason to keep the gas tank at least half-full is to reduce the chances of sediment pick-up at the fuel pump inlet strainer. A restricted strainer can starve the pump, causing it to overheat and fail.
A faulty electric fuel pump can cause various symptoms including a loud pump whine, engine no-start, hesitation, poor performance and stalling. If your car demonstrates any of these performance problems, have it checked out by a qualified service technician. Replacing the fuel pump generally involves removal of the fuel tank.
Description: The fuel tank is usually made of stamped steel or plastic. The tank is held in place with steel straps. In some cases, a bracket-and-strap arrangement is used.
Purpose: The fuel tank stores gasoline for the engine, holds the electric fuel pump and sending unit, and provides a connection to the vapour collection/recovery components of the emissions system. The tank also has a filler neck, which restricts fuelling to unleaded fuel nozzles. On 1996 and newer cars, the mouth of the filler neck is designed specially for OBDII-compatible gas caps.
Maintenance Tips/Suggestions: Unless damaged, fuel tanks last for the life of the vehicle. On many cars, the fuel tank needs to be removed in order to replace the fuel pump. On 1996 and newer cars, a light on the dash, labeled SERVICE ENGINE SOON or CHECK ENGINE may turn on if the gas cap is left loose after refueling. Make sure the gas cap is always installed properly after you refuel. Turn the cap to the right until it clicks in place.
Description: The gas cap consists of a plastic body with either threads (older caps) or lugs that locates into the filler neck of the fuel tank. Quality caps incorporate finely calibrated springs and valves. Caps may come in standard or locking types that minimize the chances of tampering with the fuel tank.
Purpose: The gas cap used to simply cover the opening of the fuel tank filler neck, but eventually strong safety and emissions initiatives pushed cap designs to accomplish other tasks. The gas cap is now a major safety component that prevents the flow of fuel back out of the tank filler when a car is in an accident, including rollovers. This helps to reduce the chances of fuel leaks and their associated dangers. The gas cap is also an integral part of the onboard diagnostics system (OBDII) and emissions control system, which are interrelated.
The cap prevents the leakage of fuel vapours from the filler neck, which can be a major source of hydrocarbon emissions. A leaking or missing gas cap can result in the release of 90 litres of fuel per year into the atmosphere.
Maintenance Tips/Suggestions: Always make sure your car’s gas cap is reinstalled properly after each fill-up. If you lose the cap, replace it immediately for safety and emissions reasons. A loose gas cap can cause your car’s SERVICE ENGINE SOON or CHECK ENGINE light to come on. If you find the cap loose, turn it to the right until it “snaps”. It may take several start-and-run cycles for the light to reset. In areas with an emissions testing program, the gas cap may be tested for its ability to hold pressure. If the cap fails, it will need to be replaced.