Fuel Delivery and Air Induction: Description and Operation

GENERAL DESCRIPTION
The fuel system for the Sportage consists of the
following components:
- Electronic fuel pump assembly
- Fuel filters (2)
- Fuel pipes (lines) and hoses
- Fuel sender assembly
- Fuel tank
- Fuel rail
- Fuel pressure regulator
- Fuel injectors (4)
- Fuel pump relay
- Pulsation damper

AIR FUEL INDUCTION SYSTEM
The air fuel induction system carries, filters, measures, and controls the flow of air into the throttle body. Fuel is metered and mixed with the air in the intake manifold. Air volume into the engine is regulated by the accelerator cable-controlled throttle plates mounted in the throttle body.

Fuel is delivered to the solenoid operated injectors through the fuel rail. Fuel pressure is controlled by a variable pressure regulator which varies fuel pressure depending on the absolute manifold pressure acting on the regulator at the time.

An electrical pulse activates a solenoid within the fuel injector body. The duration of the pulse is determined by the ECM. The ECM varies the pulse duration based upon the amount of air passing through the mass air flow sensor and the engine speed which is determined by the crankshaft sensor.

A throttle position sensor attached to the throttle plate shaft signals the ECM of the throttle position and the rate of the throttle movement. These signals influence the injector pulse duration.

The ECM-controlled idle air control valve supplies extra air to maintain idle speed. Extra air is supplied to increase idle speed when the engine is cold. Idle speed is increased when the air conditioning compressor is engaged or when mechanical load affects idle speed.

Crankcase gases are vented to the intake manifold by the positive crankcase ventilation PVC valve. The PCV valve is operated by intake manifold vacuum. At idle the PCV valve opens slightly and allows some crankcase gases into the combustion chamber. As rpm increase, the PCV valve opening increases allowing a larger volume of gases into the intake manifold.

ELECTRONIC FUEL PUMP ASSEMBLY
The electronic fuel pump assembly supplies filtered, pressurized fuel to each fuel injector through the fuel rail. The fuel pump assembly is mounted in the fuel tank to reduce pump operating noise. It is mounted with and connected to the fuel sending assembly. Both assemblies are removed from and installed into the fuel tank as a single unit.

The fuel pump is an electric pump controlled by the engine control module (ECM) through the fuel pump relay. When the ECM commands the fuel pump relay to operate, the motor rotates an impeller within the pump assembly. This causes fuel within the fuel tank to be drawn into the fuel inlet port. Fuel is pumped out to the throttle body and fuel rail and injectors under pressure through the fuel feed pipe and hose. The fuel pressure is retained when the fuel pump is not running by means of a control valve located within the pump. Excess fuel is returned to the fuel tank by means of a fuel return pipe and hose.

FUEL FILTERS
A steel in-line fuel filter is used in the fuel feed pipe ahead of the fuel injector. The filter housing is constructed to withstand temperature changes and exposure. It has a paper filter element which traps particles that could damage the fuel injection system. A screen filter in the fuel pump assembly filters out particles in the fuel tank further protecting the system.

FUEL PIPES AND HOSES
Fuel feed and return pipes (lines) and tubes carry fuel from the fuel tank to the fuel rail and back to the fuel tank. These pipes and tubes are attached to the underbody of the vehicle and must be inspected for kinks or dents which may restrict fuel flow.

Fuel vapor pipes and hoses carry fuel vapors from the fuel tank to the evaporative emissions canister located in the engine compartment. The fuel vapors are stored in the canister when the engine is not running. When the engine is running at normal operating temperature, and the accelerator pedal is depressed, the engine control module (ECM) will command the evaporative emission solenoid purge valve to open and allow the stored fuel vapors to be purged into the intake manifold and be absorbed into the combustion process.

FUEL SENDER ASSEMBLY
The fuel sending system consists of a float, float arm, and a variable resistor. Fuel level is measured by the position of the float in the fuel tank, and is indicated by a gauge in the instrument panel cluster assembly. When the fuel level changes, the float position changes. The change in float position increases or decreases the resistance of the variable resistor. The change in resistance causes the position of the fuel gauge readout to change.

FUEL TANK
The fuel tank is used to store fuel for the vehicle. It has a 15.8 gallon (60 liter) fuel capacity. The tank is formed from steel and is located directly in front of the rear wheels in back of and below the rear seat.

The fuel tank is held in place with five bolts. The tank is protected by a gravel shield to which it is mounted. The shape of the tank allows for a constant supply of fuel around the fuel pump screen filter during low fuel conditions and during aggressive vehicle maneuvers. The fuel inlet port on the tank is equipped with an inlet valve. The fuel tank inlet valve prevents fuel from spewing into the fuel filler neck during abnormal vehicle driving conditions.

To maintain proper fuel system pressure, it is imperative that the fuel filler cap be functioning properly and that it "Clicks" when screwed into the filler neck of the gas tank.

The fuel tank, along with its pipes and hoses, should be checked for road damage which could result in leakage. Also inspect the fuel filler cap for a correct seal and indications of physical damage.

FUEL PRESSURE REGULATOR VALVE

The pressure regulator regulates the injection pressure so that it is maintained at a pressure greater than 290 kpa(40.5 psi) than the pressure in the intake manifold.

The pressure regulator consist of a diaphragm, a spring and a fuel return pipe.

The calibrated spring pressure against the diaphragm and close off return pipe.

The system pressure reflects the amount of fuel pressure required to open the return pipe.

The fuel tank is filled through the fuel filler inlet port covered by a protective control-opened panel on the right side of the vehicle.

FUEL TANK PRESSURE SENSOR
The fuel tank pressure sensor located at the fuel tank is an integral part of the monitoring system. The fuel tank pressure sensor checks purge valve operation and leak detection in the evaporative emissions system by monitoring pressure and vacuum levels in the fuel tank during and between purge operating cycles.