Fuel Supply Component Description. Buick GL7 (Export) 2000

For 1990-2009 cars

### System Overview

The fuel tank stores the fuel supply. An electric fuel pump, located in the fuel tank within the modular fuel sender assembly, pumps fuel through an in-line fuel filter to the fuel rail assembly. The pump provides a higher fuel pressure than is needed by the injectors. The fuel pressure regulator keeps the fuel available to the injectors at a regulated pressure. A separate fuel pipe is used to return fuel to the fuel tank.

Unleaded fuel must be used with all gasoline engines for proper emission control system operation. Using unleaded fuel will also decrease spark plug fouling and extend the engine oil life. Leaded fuel can damage the emission control system, and the use of leaded fuel can result in the loss of emission warranty coverage.

All vehicles with gasoline engines are equipped with an evaporative emission system that minimizes the escape of fuel vapors to the atmosphere.

### Fuel Tank

The fuel tank (1) is located midway on the left inside of the vehicle. The fuel tank is molded from high density polyethylene and is held in place by 3 metal straps that secure the tank to the vehicle. The fuel tank shape includes a reservoir in order to maintain a constant supply of fuel around the fuel pump strainer during low fuel conditions and aggressive vehicle maneuvers. A filler pipe check-valve tube is attached to the fuel tank and extends from the fuel tank inlet to the reservoir. The fuel tank filler pipe check-valve is located inside the check-valve tube and prevents fuel from splashing back out of the fuel tank filler pipe during refueling.

The tank also contains a fuel vapor vent valve with roll-over protection. The vent valve also features a 2-phase vent calibration which increases fuel vapor flow to the canister when operating temperatures increase the fuel tank pressure beyond an established threshold.

The fuel tank contains several rollover valves that prevents fuel from entering the fuel pipes in the event of a vehicle rollover. The rollover valves are not repairable.

### Fuel Tank Filler Pipe

In order to prevent refueling with leaded fuel, the fuel tank filler pipe (2) has a built-in restrictor and deflector. The fuel tank filler pipe is connected to the fuel tank filler extension (1) by clamps.

### Fuel Tank Filler Pipe Cap

The fuel tank filler pipe is equipped with a quarter-turn type fuel filler pipe cap. In order to install the fuel filler pipe cap, turn the cap clockwise until a clicking noises is heard. A built-in device indicates that the cap is fully seated. The fuel pipe filler cap has a tether connected to the fuel fill door.

### Modular Fuel Sender Assembly

The modular fuel sender assembly is serviced as a complete assembly and only the fuel level sensor and fuel sender strainer can be replaced separately.

The modular fuel sender assembly consists of the following major components:

• | The fuel sender strainer (3)

• | The fuel pump strainer

• | The roll-over valve

• | The fuel level sensor (4)

### Fuel Level Sensor

The fuel level sensor consists of the float, the wire float arm, and the ceramic resistor card. The fuel level sensor is mounted on the modular fuel sender assembly and is used as an input to the PCM. The PCM uses this information as a fuel level input for various diagnostics. In addition, the PCM transmits the fuel level over the Class 2 communication circuit to the instrument panel cluster (IPC). This information is used for the IPC fuel gauge, and low fuel warning indicator if applicable.

### Fuel Pump

The fuel pump is mounted in the fuel reservoir within the modular fuel sender. The fuel pump is an electric high pressure gerotor pump. The fuel is pumped to the fuel rail at a specified flow and pressure. Excess fuel returns to the fuel tank by a return pipe. The fuel pump delivers a constant flow of fuel to the engine even during low fuel conditions and aggressive vehicle maneuvers. The electric fuel pump operation is controlled by the powertrain control module (PCM) through a fuel pump relay. The fuel pump flex pipe acts to dampen the fuel pulses and noise generated by the fuel pump. The fuel pump is serviced as part of the modular fuel sender assembly.

### Fuel Pressure Regulator Assembly

The fuel pressure regulator attaches to the fuel rail on the fuel return side. The fuel pressure is a diaphragm operated relief valve and is referenced to manifold vacuum. If the fuel pressure is too low, poor performance could result. If the pressure is to high, excessive odor and a diagnostic trouble code (DTC) may result.

### Fuel Pump Strainer

The fuel pump strainer attaches to the lower end of the modular fuel sender assembly. The fuel pump strainer is made of woven plastic. The functions of the fuel pump strainer are to filter contaminants and to wick fuel. The life of the fuel pump strainer is generally considered to be that of the fuel pump. The strainer is self-cleaning and normally requires no maintenance. Fuel stoppage at this point indicates that the fuel tank contains an abnormal amount of sediment or water, in which case the tank should be thoroughly cleaned and the strainer replaced.

### Roll-over valve

The fuel system contains a rollover valve that prevents fuel from entering the fuel pipes in the event of a vehicle rollover. The rollover valve is serviced as part of the modular fuel sender assembly.

### In-Pipe Fuel Filter

The fuel feed pipe has a steel fuel filter installed ahead of the fuel injection system. The paper filter element (2) traps particles in the fuel that may damage the injection system. The filter housing (1) is made to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature. The fuel filter has a quick-connect inlet fitting and a threaded outlet fitting. The threaded fitting is sealed with an O-ring. There is no service interval for fuel filter replacement. Replace a restricted fuel filter.

### Fuel Feed and Fuel Return Pipes

The fuel feed and fuel return pipes carry fuel from the modular fuel sender assembly to the fuel injection system and back to the modular fuel sender assembly.

### Nylon Fuel Pipes

Nylon fuel pipes are designed to perform the same job as the steel or rubber fuel lines they replace. Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to fuel additives and changes in temperature. There are 2 sizes used: a 3/8 inch ID for the fuel feed, and a 5/16 inch ID for the fuel return and on the modular sender. Nylon fuel pipes are somewhat flexible and can be formed around gradual turns. However, if forced into sharp bends, nylon pipes will kink and restrict the fuel flow. Also, nylon pipes may become stiffer and are more likely to kink once the pipes are exposed to fuel. Special care should be taken when working on a vehicle with nylon pipes.

### Quick Connect Fittings

Quick-connect type fittings provide a simplified means of installing and connecting fuel system components. Depending on the vehicle model, there are 2 types of quick-connect fittings, each used at different locations in the fuel system. Each type of quick-connect fitting consists of a unique female connector and a compatible male fuel pipe end. O-rings, located inside the female connector, provide the fuel seal. Integral locking tabs or fingers hold the quick-connect fittings together.

### Fuel Pipe O-rings

Fuel feed and return pipe threaded connections at the fuel rail and fuel filter are sealed with replaceable O-ring seals. These O-rings seals are made of special material, and should only be serviced with the correct service part.