Part 1

Fuel System Description

The fuel system is comprised of 2 subsystems. The fuel supply system and the fuel metering system. The correct amount of fuel can not be delivered to the engine cylinders without a constant supply of air from the air intake system. The air intake system provides measured clean air to each cylinder for proper mixture with the pressurized fuel. The powertrain control module (PCM), along with the information sensors and switches, controls the activity between all 3 systems.

Fuel System Components




1 - Fuel Tank
2 - Fuel Sender Assembly, includes fuel pump
3 - Fuel Filler Pipe
4 - EVAP Canister
5 - Quick Connect Fuel Line Fitting, Tank
6 - Fuel and EVAP Lines
7 - Quick Connect Fuel Line Fitting, Engine
8 - Fuel Rail
9 - Fuel Injectors

The fuel supply system is a returnless on-demand design, that reduces evaporative emissions. The fuel metering system is a sequential fuel injection (SFI) design. The function of the fuel metering system is to deliver the correct amount of fuel to the engine under all operating conditions. The main component of the vehicle's fuel metering system is the fuel injectors. There is one fuel injector for each cylinder. The fuel injectors are controlled sequentially by the PCM. The PCM bases the control of the fuel injectors on several important engine parameters. These engine parameters include the following:

* The mass air flow (MAF) sensor
* The intake air temperature (IAT) sensor
* The engine coolant temperature (ECT) sensor
* The throttle position (TP) sensors
* The accelerator pedal position (APP) sensors
* The engine speed (RPM)
* The heated oxygen sensor (HO2S)

The engine is designed to use only unleaded fuel. Unleaded fuel must be used for proper emission control system operation. Using unleaded fuel will also decrease spark plug fouling and extend engine oil life. Leaded fuel can damage the emission control system. The use of leaded fuel can result in the loss of emission warranty coverage.

The vehicle fuel system is equipped with an evaporative emission (EVAP) control system that minimizes the release of fuel vapors to the atmosphere. For more information on the EVAP system, refer to Evaporative Emission Control System Description (Evaporative Emission Control System Description).

Fuel Supply System




1 - Fuel Pressure Gauge Adapter J 42982
2 - Fuel Feed Pipe
3 - Fuel Sender Assembly
4 - Fuel Tank
5 - Fuel Pressure Regulator
6 - Fuel Pump
7 - Fuel Sender (gauge)
8 - Fuel Filter
9 - Pinch Off Area
10 - Fuel Pressure Gauge J 34730-1A
11 - Fuel Injectors
12 - Fuel Rail

The supply of fuel is stored in the fuel tank. An electric fuel pump pressurizes the fuel through to the fuel filter and out to the fuel lines and the fuel rail. The electric fuel pump is suspended from the top of the fuel tank as part of the fuel sender assembly. The fuel pump is designed to provide fuel at a pressure above the regulated pressure needed by the fuel injectors. The fuel pressure regulator keeps the fuel supplied to the fuel injectors at the regulated pressure.

The fuel pressure regulator is located inside of the fuel tank and is part of the fuel sender assembly. Locating the fuel pressure regulator in the fuel tank eliminates the need for a return line from the fuel rail. A returnless system reduces the internal temperature of the fuel tank resulting in lower evaporative emissions.

The fuel system is also equipped with an enhanced evaporative emission (EVAP) system and an on-board refueling vapor recovery (ORVR) system. Together the 2 systems minimize the release of fuel vapors to the atmosphere.

Fuel Tank Assembly




1 - Fuel Supply Line
2 - Retaining Clip
3 - ORVR Vent Line
4 - Fuel Filler Cap
5 - Fuel Filler Pipe Assembly
6 - Fuel Filler Hose
7 - Fuel Filler Hose Protector
8 - Fuel Tank Straps
9 - Fuel Tank
10 - Fuel Sender Assembly Gasket
11 - Fuel Sender Assembly
12 - Fuel Tank Lock Ring

Fuel Tank

The fuel tank is made of a composite material. The composite material is actually several layers of materials. The outside and inside layers are a high density polyethylene, with a center layer of recycled material and ethylene vinyl alcohol copolymer. The fuel tank is located beneath the rear seat area. The tank is held in place with 2 straps that are secured with bolts. The shape of this tank was designed to allow for a constant supply of fuel around the fuel pump strainer during low fuel conditions and also during aggressive vehicle maneuvers. The fuel inlet port on the tank is equipped with an inlet valve. This fuel tank inlet valve prevents the fuel from spewing into the fuel filler neck during aggressive vehicle maneuvers or vehicle rollovers. The fuel tank is equipped with an on-board refueling vapor recovery (ORVR) system.

Fuel Tank Filler Neck

In order to prevent refueling with diesel fuel, the fuel filler neck has a built-in restrictor and deflector. The opening of the restrictor admits only the smaller unleaded fuel nozzle. The nozzle must be fully inserted to bypass the deflector. Any attempt at refueling with leaded fuel will result in fuel splashing out of the filler neck.

Fuel Filler Cap





Caution: If a fuel tank filler pipe cap requires replacement, use only a fuel tank filler pipe cap with the same features. Failure to use the correct fuel tank filler pipe cap can result in a serious malfunction of the fuel system.

The fuel filler cap is an updated version of the screw thread design. This latest version of the screw on cap provides only one click with a firm stop, when the cap is correctly installed. Tightening the fuel cap until the one click is heard assures a sealed fuel system. The fuel cap is a pressure-vacuum type operation. To install the cap, turn the cap clockwise until the cap stops and the one click is heard. This indicates that the fuel filler cap gasket (1) is fully seated.

A vacuum relief valve is incorporated into the fuel filler cap. If the pressure in the fuel tank becomes negative (vacuum), the relief valve opens to relieve the pressure created within the fuel tank. Only when the vacuum becomes excessive within the tank does this occur. Vacuum pressure is also vented through the tank pressure control valve which is located on the top of the fuel tank.

A pressure relief valve is also located in the fuel filler cap. The pressure of the fuel vapor within the tank should exceed that for which the fuel system is designed, the pressure relief valve opens, and the excess pressure is vented to the atmosphere.